Sensor LDU 68 Series User manual
Website: www.sensortechniques.com e-mail: [email protected]
Tel:+44 (0)1446 771185 Fax:+44 (0)1446 771186
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 1 LDU 68 Series Manual
Load Cell Digitizing Unit Type LDU 68 Series
MANUAL
Firmware Version 68.181 v4.0x
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 2 LDU 68 Series Manual
1 INTRODUCTION & SPECIFICATIONS 3
2 COMMUNICATIONS & GETTING STARTED 4
2.1 Serial Interface 4
2.2 Command Language 4
2.3 Setup baud rate / device address 5
2.4 Display mode 5
2.5 Getting Started 5
3 HARDWARE & WIRING 6
3.1 Load Cell Connections 7
3.2 Power Connections 7
3.3 Logic Inputs and Logic Outputs 7
3.4 Communication Connections 7
4 COMMANDS OVERVIEW 10
5 COMMANDS 12
5.1 System diagnostic Commands - ID, IV, IS, SR 13
5.2 Checkweigher Commands - SD, MT, TE, TL, TR, GA, SA 15
5.3 Calibration Commands - CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI 18
5.4 Motion detection Commands - NR, NT 21
5.5 Filter setting Commands - FL, FF, UR 22
5.6 Set Zero/Tare and Reset Zero/Tare Commands - SZ, RZ, ST, RT 23
5.7 Output Commands - GG, GN, GT, GS, GF, GW, GA 25
5.8 Auto-transmit Commands - SG, SN, SF, SW, SA 27
5.9 Commands for external I/O control - IN, IO, IM 28
5.10 Setpoint Commands - Sn, Hn, An 30
5.11 Communication setup Commands - AD, CL, BR, DX, OP, TD 32
5.12 Save calibration, setup & setpoint parameters Commands - CS, WP, SS, GI, PI 34
6 CALIBRATION PROCEDURE 35
7 USE IN “APPROVED” APPLICATIONS (LDU 68.1 ONLY) 36
8 SOFTWARE (FIRMWARE) DOWNLOADS 37
8.1 Firmware updates for the LDU XX.X series 37
9 UNIT ADAPTOR CONNECTION DETAIL 38
9.1 UA 77.1 Unit Adaptor with built-in RS422 to RS232 converter 38
9.2 UA73.2 Standard Unit Adaptor 39
10 USB to RS422/485 CONVERTER WIRING (Multi-drop application) 40
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 3 LDU 68 Series Manual
The LDU 68 amplifier series are precise, mid-speed digital amplifiers for weighing and force
measurements applications which use strain gauge (SG) based sensors. The LDU 68.1 can be used
in both legal for trade and industrial applications. The LDU 68.2 is not Weights & Measures
approved but still offers a lower cost solution for industrial applications. Both devices feature full
multi-drop communication capability and can be programmed using the straight forward ASCII
command set.
The LDU XX.X series and the DAS72.1 amplifier with on-board digital display, use the same
command set. So you can connect up to 32 SG amplifiers of either the LDU X.XX series or the
DAS72.1 types onto a single RS 485 bus.
The LDU 68 series with its high precision 17 bit A to D converter and a mid-speed sample rate of 80
samples per second, is particularly suitable for static measurements and control.
Accuracy Class
EU Type approved
Linearity
Load Cell Excitation
Load Cell Drive Capability
Analogue Input Range
Minimum input per vsi
Resolution
Conversion rate
Digital filter
Calibration
Computer Interface
Weighing functions
Inputs
Outputs
Temperature effects
Temperature range
Enclosure
Dimensions
Power supply
Options
EMC/Approvals
III or IIII (LDU 68.1 ONLY)
R76 10000 Divisions (LDU 68.1 ONLY)
<0.005% Full Scale
5 V DC
Input impedance 80-5000 Ohms (12-14V DC Supply), 6-wire technique
Input Impedance 350-5000 Ohms (14-24V DC Supply), 6-wire technique
±2.48 mV/V (bipolar, for push/pull weighing or tension/compression forces)
50nV per interval non-approved, 1.0µV per interval approved
Internal max ±165,000 counts, external max ± 99,999 counts
Up to 80 measurements per second
0.02Hz - 5Hz second order (i.e.40 dB/decade)
Software calibration and set up
RS485 or RS422 full duplex, 9600 ... 115200 Baud; up to 32 devices on a bus.
Zero, gross, tare, net, filter etc.
2 opto-isolated inputs, 10-30 VDC max. 3 mA
2 open collector outputs, <30 V DC
On zero:<10 ppm/°K (LDU 68.1):<50 ppm/°K (LDU 68.2)
On span:<5 ppm/°K (LDU 68.1):<40 ppm/°K (LDU 68.2)
-10°C to +50°C (compensated); -20°C to +60°C (storage)
Tin plated steel enclosure sealed to IP 40
82 x 31 6 mm, weight approx. 30 g; with adaptor board 91 x 41 x 12 mm
approx. 50 g
12 ... 24 V DC ±10%, <60mA, not galvanically isolated.
Adaptor board UA73.2 (passive) or UA77.1 (RS422 to RS232)
CE 73/23/EEC; 93/98/EEC and 89/336/EEC
All dimensions in mm. Dimensions and specifications are subject to change without notice.
1 INTRODUCTION & SPECIFICATIONS
Technical Specifications of the LDU 68 Series:
Issue 1h
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TECHNIQUES LIMITED
Page 2 LDU 68 Series Manual
1 INTRODUCTION & SPECIFICATIONS 3
2 COMMUNICATIONS & GETTING STARTED 4
2.1 Serial Interface 4
2.2 Command Language 4
2.3 Setup baud rate / device address 5
2.4 Display mode 5
2.5 Getting Started 5
3 HARDWARE & WIRING 6
3.1 Load Cell Connections 7
3.2 Power Connections 7
3.3 Logic Inputs and Logic Outputs 7
3.4 Communication Connections 7
4 COMMANDS OVERVIEW 10
5 COMMANDS 12
5.1 System diagnostic Commands - ID, IV, IS, SR 13
5.2 Checkweigher Commands - SD, MT, TE, TL, TR, GA, SA 15
5.3 Calibration Commands - CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI 18
5.4 Motion detection Commands - NR, NT 21
5.5 Filter setting Commands - FL, FF, UR 22
5.6 Set Zero/Tare and Reset Zero/Tare Commands - SZ, RZ, ST, RT 23
5.7 Output Commands - GG, GN, GT, GS, GF, GW, GA 25
5.8 Auto-transmit Commands - SG, SN, SF, SW, SA 27
5.9 Commands for external I/O control - IN, IO, IM 28
5.10 Setpoint Commands - Sn, Hn, An 30
5.11 Communication setup Commands - AD, CL, BR, DX, OP, TD 32
5.12 Save calibration, setup & setpoint parameters Commands - CS, WP, SS, GI, PI 34
6 CALIBRATION PROCEDURE 35
7 USE IN “APPROVED” APPLICATIONS (LDU 68.1 ONLY) 36
8 SOFTWARE (FIRMWARE) DOWNLOADS 37
8.1 Firmware updates for the LDU XX.X series 37
9 UNIT ADAPTOR CONNECTION DETAIL 38
9.1 UA 77.1 Unit Adaptor with built-in RS422 to RS232 converter 38
9.2 UA73.2 Standard Unit Adaptor 39
10 USB to RS422/485 CONVERTER WIRING (Multi-drop application) 40
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 3 LDU 68 Series Manual
The LDU 68 amplifier series are precise, mid-speed digital amplifiers for weighing and force
measurements applications which use strain gauge (SG) based sensors. The LDU 68.1 can be used
in both legal for trade and industrial applications. The LDU 68.2 is not Weights & Measures
approved but still offers a lower cost solution for industrial applications. Both devices feature full
multi-drop communication capability and can be programmed using the straight forward ASCII
command set.
The LDU XX.X series and the DAS72.1 amplifier with on-board digital display, use the same
command set. So you can connect up to 32 SG amplifiers of either the LDU X.XX series or the
DAS72.1 types onto a single RS 485 bus.
The LDU 68 series with its high precision 17 bit A to D converter and a mid-speed sample rate of 80
samples per second, is particularly suitable for static measurements and control.
Accuracy Class
EU Type approved
Linearity
Load Cell Excitation
Load Cell Drive Capability
Analogue Input Range
Minimum input per vsi
Resolution
Conversion rate
Digital filter
Calibration
Computer Interface
Weighing functions
Inputs
Outputs
Temperature effects
Temperature range
Enclosure
Dimensions
Power supply
Options
EMC/Approvals
III or IIII (LDU 68.1 ONLY)
R76 10000 Divisions (LDU 68.1 ONLY)
<0.005% Full Scale
5 V DC
Input impedance 80-5000 Ohms (12-14V DC Supply), 6-wire technique
Input Impedance 350-5000 Ohms (14-24V DC Supply), 6-wire technique
±2.48 mV/V (bipolar, for push/pull weighing or tension/compression forces)
50nV per interval non-approved, 1.0µV per interval approved
Internal max ±165,000 counts, external max ± 99,999 counts
Up to 80 measurements per second
0.02Hz - 5Hz second order (i.e.40 dB/decade)
Software calibration and set up
RS485 or RS422 full duplex, 9600 ... 115200 Baud; up to 32 devices on a bus.
Zero, gross, tare, net, filter etc.
2 opto-isolated inputs, 10-30 VDC max. 3 mA
2 open collector outputs, <30 V DC
On zero:<10 ppm/°K (LDU 68.1):<50 ppm/°K (LDU 68.2)
On span:<5 ppm/°K (LDU 68.1):<40 ppm/°K (LDU 68.2)
-10°C to +50°C (compensated); -20°C to +60°C (storage)
Tin plated steel enclosure sealed to IP 40
82 x 31 6 mm, weight approx. 30 g; with adaptor board 91 x 41 x 12 mm
approx. 50 g
12 ... 24 V DC ±10%, <60mA, not galvanically isolated.
Adaptor board UA73.2 (passive) or UA77.1 (RS422 to RS232)
CE 73/23/EEC; 93/98/EEC and 89/336/EEC
All dimensions in mm. Dimensions and specifications are subject to change without notice.
1 INTRODUCTION & SPECIFICATIONS
Technical Specifications of the LDU 68 Series:
Issue 1h
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TECHNIQUES LIMITED
Page 4 LDU68 Series Manual
The command set for the LDU XX.X series is based on a simple ASCII format. This consists of a 2
capital letter code which enables the user to setup the device, get results or check parameters.
Example:
An LDU XX.X with the address or channel number 1 is connected via the RS485 port to a bus
system. You want to get the net weight from this device.
In this manual a space is represented by “_” and Enter (CR/LF) by “¿”
The command OP_2 opens the communication channel to device #2 and closes communication
with device #1. Now device #2 acknowledges that it is active (OK) and responds to any commands
on the bus. Communication with device #2 will be closed by another OP command (for another
device on the bus e.g. OP_5) or by the close command e.g. CL_2.
Each OP_X command implies a CL command to all other devices on the bus except #X. This makes
the address structure easier and improves system performance.
2 COMMUNICATIONS & GETTING STARTED
2.1 Serial Interface
Communication with the LDU xx.x series is via the RS422/RS485 port. The data format is the
familiar 8/N/1 structure (8 data bits, no parity, 1 stop bit). The LDU xx.x can communicate at the
following baud rates: 9600, 19200, 38400, 57600, 115200 baud.
RS422
! Connection using a 4 wire technique.
! Point to Point connection
RS485
! Connection using 2 or 4 wire techniques
! Multi-drop connection possible with up to 32 LDU XX.X on a bus.
! Half duplex only (DX=0).
(RS232)
! An optional adaptor board model UA77.1 is available, which has a built-in RS422 to RS232
converter
2.2 Command Language
Master (PC / PLC) sends Slave (LDU XX.X) responds Status
OP_1¿
GN¿
OK
N+123.45
Device number 1 ready
Open Device number 1
Net weight value with sign & decimal point
Get Net weight value
Issue 1h Page 5 LDU 68 Series Manual
Ideas in Measuring ..
TECHNIQUES LIMITED
2.3 Setup Baud rate / Device Address
The factory default baud rate is 9600 baud. The factory default device address is 0. Under normal
circumstances the baud rate can be changed or viewed using the BR command (Page 30). Similarly,
the device address can be changed or viewed using the AD command (Page 30). If however you do
not know the device baud rate or address, the LDU can be put into a special configuration mode
which allows the baud rate and device address to be reset. On the under side of the LDU PCB are a
set of special solder pads (SW3) - See diagram on page 6. If these solder pads are bridged (shorted
together) then the LDU will enter the special configuration mode on power up.
Baud Rate (In Configuration Mode)
With SW3 pads bridged, the LDU XX.X will enter a special baud rate search mode on power up.
This involves the LDU waiting for a space character (0x20) to be received. The time duration of this
character is measured by the LDU and its baud rate will be set accordingly - i.e. the baud rate of the
terminal sending the space character will be used by the LDU. The factory default baud rate is 9600
baud.
Address Settings (In Configuration Mode)
2.4 Display Mode
With SW3 pads bridged, the LDU XX.X will enter a special configuration mode on power up. It is
possible to set the network address of the device using the AD command. (Address range between
0 and 255). Setting the address to 0 will set it into continuously active mode, where the device will
listen and respond to any command on the bus without the need for an OP xxx command. Factory
default: Address 0
2.5 Getting Started
You will require a:
! PC or PLC with either a RS422 or RS485 communication port
! If you are using a PC or PLC with an RS232 port, you will require a RS422 to RS232 converter
(optional unit adaptor UA77.1)
! Interconnecting cabling - See the wiring diagram on Page 6
! A load cell / scale with test weights or a load cell simulator
! A 12-24 V DC power supply capable of delivering approx. 100mA for each LDU and load cell
! One or more LDU 68.1/68.2
! The DOP 4 software*
Refer to the wiring diagram on Page 6
*The DOP 4 software with graphical user interface and oscilloscope function is now available for
Windows PCs. Download the latest version of the DOP 4 software from
http://www.haubac.com/haubac.asp?p1=167 together with Quick Start and Users Manuals
In addition to the standard filters, a filter factor (FF) has been added specifically for when the LDU
68 series is used with an external display. The Filter Factor allows a rolling average to be set up
which gives a more stable result on an external display The Get Filtered value (GF) and Send
Filtered value (SF) commands can be used to get or auto-transmit the filtered values for an external
display.
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 4 LDU68 Series Manual
The command set for the LDU XX.X series is based on a simple ASCII format. This consists of a 2
capital letter code which enables the user to setup the device, get results or check parameters.
Example:
An LDU XX.X with the address or channel number 1 is connected via the RS485 port to a bus
system. You want to get the net weight from this device.
In this manual a space is represented by “_” and Enter (CR/LF) by “¿”
The command OP_2 opens the communication channel to device #2 and closes communication
with device #1. Now device #2 acknowledges that it is active (OK) and responds to any commands
on the bus. Communication with device #2 will be closed by another OP command (for another
device on the bus e.g. OP_5) or by the close command e.g. CL_2.
Each OP_X command implies a CL command to all other devices on the bus except #X. This makes
the address structure easier and improves system performance.
2 COMMUNICATIONS & GETTING STARTED
2.1 Serial Interface
Communication with the LDU xx.x series is via the RS422/RS485 port. The data format is the
familiar 8/N/1 structure (8 data bits, no parity, 1 stop bit). The LDU xx.x can communicate at the
following baud rates: 9600, 19200, 38400, 57600, 115200 baud.
RS422
! Connection using a 4 wire technique.
! Point to Point connection
RS485
! Connection using 2 or 4 wire techniques
! Multi-drop connection possible with up to 32 LDU XX.X on a bus.
! Half duplex only (DX=0).
(RS232)
! An optional adaptor board model UA77.1 is available, which has a built-in RS422 to RS232
converter
2.2 Command Language
Master (PC / PLC) sends Slave (LDU XX.X) responds Status
OP_1¿
GN¿
OK
N+123.45
Device number 1 ready
Open Device number 1
Net weight value with sign & decimal point
Get Net weight value
Issue 1h Page 5 LDU 68 Series Manual
Ideas in Measuring ..
TECHNIQUES LIMITED
2.3 Setup Baud rate / Device Address
The factory default baud rate is 9600 baud. The factory default device address is 0. Under normal
circumstances the baud rate can be changed or viewed using the BR command (Page 30). Similarly,
the device address can be changed or viewed using the AD command (Page 30). If however you do
not know the device baud rate or address, the LDU can be put into a special configuration mode
which allows the baud rate and device address to be reset. On the under side of the LDU PCB are a
set of special solder pads (SW3) - See diagram on page 6. If these solder pads are bridged (shorted
together) then the LDU will enter the special configuration mode on power up.
Baud Rate (In Configuration Mode)
With SW3 pads bridged, the LDU XX.X will enter a special baud rate search mode on power up.
This involves the LDU waiting for a space character (0x20) to be received. The time duration of this
character is measured by the LDU and its baud rate will be set accordingly - i.e. the baud rate of the
terminal sending the space character will be used by the LDU. The factory default baud rate is 9600
baud.
Address Settings (In Configuration Mode)
2.4 Display Mode
With SW3 pads bridged, the LDU XX.X will enter a special configuration mode on power up. It is
possible to set the network address of the device using the AD command. (Address range between
0 and 255). Setting the address to 0 will set it into continuously active mode, where the device will
listen and respond to any command on the bus without the need for an OP xxx command. Factory
default: Address 0
2.5 Getting Started
You will require a:
! PC or PLC with either a RS422 or RS485 communication port
! If you are using a PC or PLC with an RS232 port, you will require a RS422 to RS232 converter
(optional unit adaptor UA77.1)
! Interconnecting cabling - See the wiring diagram on Page 6
! A load cell / scale with test weights or a load cell simulator
! A 12-24 V DC power supply capable of delivering approx. 100mA for each LDU and load cell
! One or more LDU 68.1/68.2
! The DOP 4 software*
Refer to the wiring diagram on Page 6
*The DOP 4 software with graphical user interface and oscilloscope function is now available for
Windows PCs. Download the latest version of the DOP 4 software from
http://www.haubac.com/haubac.asp?p1=167 together with Quick Start and Users Manuals
In addition to the standard filters, a filter factor (FF) has been added specifically for when the LDU
68 series is used with an external display. The Filter Factor allows a rolling average to be set up
which gives a more stable result on an external display The Get Filtered value (GF) and Send
Filtered value (SF) commands can be used to get or auto-transmit the filtered values for an external
display.
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 6 LDU68 Series Manual
Standard Unit with RS422 Point to Point Connections
Standard Unit with RS485 Multi-drop Connections
Top view
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Tx+
Tx-
Rx+
Rx-
Signal gnd
+12 to 24V
Gnd
Power Supply Gnd
+ Power Supply
Signal Gnd
Power Supply Gnd
Common +Rx (Pin 10) to +Tx (Pin 13)
and -Rx (Pin 11) to -Tx (Pin12)
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Signal Gnd
Power Supply Gnd
Common +Rx (Pin 10) to +Tx (Pin 13)
and -Rx (Pin 11) to -Tx (Pin12)
Fit a 120 Ohm terminator to the last
device on the bus
RS485 Interface
120 Ohm
120 Ohm R1
R2
In multi-drop configuration, there
can be brief periods when no
transmitter is enabled, and the
network is therefore allowed to
float. To avoid this, pull up/pull
down resistors (R1 & R2) can be
added. Typical values of R1 & R2
for a 12V supply voltage will be
1K2 Ohms. For lower supply
voltages such as 5V, the values of
R1 & R2 can be lowered to 470
Ohms.
Fit 120 Ohm terminator
at host end
3 HARDWARE & WIRING DIAGRAMS
Issue 1h
Bottom view
Sw1 & Sw2:
Close for 4-wire
load cell
Sw3: Close to enter
configuration mode
Sw5: Close to connect
power supply ground to
chassis
Sw4: Do NOT close.
Used for program
download only.
Sw3
Sw5
Sw4
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 7 LDU 68 Series Manual
The load cell(s) are connected to pins 0 to 6 of the LDU 68.x.
Pins 1 & 6 provide excitation (5 V DC) to the load cell circuit, pin 1 being positive excitation (+Exc)
and pin 6 negative excitation (-Exc).
Pins 3 & 4 are the signal inputs to the LDU 68.x from the load cell circuit, pin 3 being the positive
signal (+Sig) and pin 4 being the negative signal (-Sig).
Pins 2 & 5 are the Sense connections for the LDU 68.x, pin 2 being the positive sense (+Sen) and
pin 5 the negative sense (-Sen). If your load cell has 6 wires ( 2 for Excitation, 2 for Signal and 2 for
Sense) the sense connections provide the LDU 68.x with the voltage that reached the load cell(s)
as opposed to the voltage that was sent. This enables the LDU 68.x to correct for voltage drops on
long cables.
If your load cell only has 4 wires you will need to link the positive excitation (+Exc) pin (Pin 1) and
the positive sense (+Sen) pin (Pin 2) and similarly the negative excitation (-Exc) pin (Pin 6) and the
negative sense (-Sen) pin (Pin 5). This can be achieved simply by solder bridging pads SW1 and
SW2 on the underside of the LDU 68.x pcb. (See diagram on Page 6)
Pin 0 provides a ground connection for the load cell cable screen or drain wire.
Power is provided to the LDU 68.x via pins 18 & 19, pin 18 being the positive supply (Pwr) 12 - 24
VDC and pin 19 being the power supply ground (Gnd) 0 V.
3.1 Load Cell Connections
3.2 Power Connections
3.3 Logic Inputs and Logic Outputs
3.4 Communication Connections
3.4.1 RS422 Point to Point 4 wire connection half or full duplex.
The standard interface on the LDU 68.x is RS422. The Tx+ connection from the host system is
connected to +Rx (Pin 10) of the LDU 68.x. Similarly the Tx- from the host is connected to -Rx (Pin
11) , the Rx- is connected to the -Tx (Pin 12) and the Rx+ is connected to the +Tx (Pin 13). The
shield connection for the RS422 cable should be connected to the power supply ground Gnd (Pin
19)
3.4.2 RS485 Multi-Drop 2 wire connection half duplex.
The LDU series can be wired in a multi-drop mode where up to 32 devices can be connected to one
bus. The +Rx (Pin 10) and +Tx (pin 13) should be commoned together and should be connected to
the A (Tx-/Rx- or D-) terminal of the host RS485 interface. The -Rx (Pin 11) and the -Tx (Pin 12)
should similarly be commoned and connected to the B (Tx+/Rx+ or D+) terminal of the host RS485
interface. The ground connection (GND) from the host RS485 should be connected to the power
supply ground of the LDUs. Termination resistors of 120 Ohm each should be placed between the B
(Tx+/Rx+ or D+) and A (Tx-/Rx- or D-) lines at host end of the bus and between the B (Tx+/Rx+ or
D+) and the A (Tx-/Rx- or D-) lines of the last device on the bus. In addition it may be necessary to
add pull up and pull down resistors (R1 & R2) to the B (Tx+/Rx+ or D+) and A (Tx-/Rx- or D-) lines to
prevent these lines ‘floating’ during periods of no transmission. Where the supply voltage to the
RS485 line driver IC is typically 5V DC for example, the value of R1 & R2 can be 470 Ohms each.
Where for example you are using a RS232 to RS485 converter with a supply voltage of 12 V DC,
the value of R1 & R2 should be increased to 1K2 Ohms (1200 Ohms).
The LDU 68.x have 2 logic inputs on pins 14 & 16 and 2 logic outputs (Open Collector) on pins 15 &
17. The common for both the logic inputs and outputs is internally connected to the ground of the
power supply so no separate common supply is required. Control signals (10 - 30 V DC) applied to
the logic inputs can be used to trigger a variety of weighing processes such as check-weighing,
filling etc. The status of the logic inputs can be read via the LDU 68.x communication port. The logic
outputs are effectively weight dependant switches. These can be used to control alarms or filling
valves etc. The load to be controlled is wired between the positive supply and the appropriate logic
output terminal on the LDU 68.x.
Issue 1h
B or D+ or Tx+/Rx+
Gnd
A or D- or Tx-/Rx-
Vcc
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Inp 3
2
Gnd
NC
Sen
0
+Pwr
Out
Rx
+
Tx
+
In
0
In
1
Rx
-
Tx
-
0
Out
1
1
Inp4
Sen5
Exc6
Gnd7
NC8
9
12
13
11
10
15
14
17
16
19
18
+
+
-
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
Exc
Gnd
TECHNIQUES LIMITED
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Sw2
Sw1
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 6 LDU68 Series Manual
Standard Unit with RS422 Point to Point Connections
Standard Unit with RS485 Multi-drop Connections
Top view
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Tx+
Tx-
Rx+
Rx-
Signal gnd
+12 to 24V
Gnd
Power Supply Gnd
+ Power Supply
Signal Gnd
Power Supply Gnd
Common +Rx (Pin 10) to +Tx (Pin 13)
and -Rx (Pin 11) to -Tx (Pin12)
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
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Signal Gnd
Power Supply Gnd
Common +Rx (Pin 10) to +Tx (Pin 13)
and -Rx (Pin 11) to -Tx (Pin12)
Fit a 120 Ohm terminator to the last
device on the bus
RS485 Interface
120 Ohm
120 Ohm R1
R2
In multi-drop configuration, there
can be brief periods when no
transmitter is enabled, and the
network is therefore allowed to
float. To avoid this, pull up/pull
down resistors (R1 & R2) can be
added. Typical values of R1 & R2
for a 12V supply voltage will be
1K2 Ohms. For lower supply
voltages such as 5V, the values of
R1 & R2 can be lowered to 470
Ohms.
Fit 120 Ohm terminator
at host end
3 HARDWARE & WIRING DIAGRAMS
Issue 1h
Bottom view
Sw1 & Sw2:
Close for 4-wire
load cell
Sw3: Close to enter
configuration mode
Sw5: Close to connect
power supply ground to
chassis
Sw4: Do NOT close.
Used for program
download only.
Sw3
Sw5
Sw4
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 7 LDU 68 Series Manual
The load cell(s) are connected to pins 0 to 6 of the LDU 68.x.
Pins 1 & 6 provide excitation (5 V DC) to the load cell circuit, pin 1 being positive excitation (+Exc)
and pin 6 negative excitation (-Exc).
Pins 3 & 4 are the signal inputs to the LDU 68.x from the load cell circuit, pin 3 being the positive
signal (+Sig) and pin 4 being the negative signal (-Sig).
Pins 2 & 5 are the Sense connections for the LDU 68.x, pin 2 being the positive sense (+Sen) and
pin 5 the negative sense (-Sen). If your load cell has 6 wires ( 2 for Excitation, 2 for Signal and 2 for
Sense) the sense connections provide the LDU 68.x with the voltage that reached the load cell(s)
as opposed to the voltage that was sent. This enables the LDU 68.x to correct for voltage drops on
long cables.
If your load cell only has 4 wires you will need to link the positive excitation (+Exc) pin (Pin 1) and
the positive sense (+Sen) pin (Pin 2) and similarly the negative excitation (-Exc) pin (Pin 6) and the
negative sense (-Sen) pin (Pin 5). This can be achieved simply by solder bridging pads SW1 and
SW2 on the underside of the LDU 68.x pcb. (See diagram on Page 6)
Pin 0 provides a ground connection for the load cell cable screen or drain wire.
Power is provided to the LDU 68.x via pins 18 & 19, pin 18 being the positive supply (Pwr) 12 - 24
VDC and pin 19 being the power supply ground (Gnd) 0 V.
3.1 Load Cell Connections
3.2 Power Connections
3.3 Logic Inputs and Logic Outputs
3.4 Communication Connections
3.4.1 RS422 Point to Point 4 wire connection half or full duplex.
The standard interface on the LDU 68.x is RS422. The Tx+ connection from the host system is
connected to +Rx (Pin 10) of the LDU 68.x. Similarly the Tx- from the host is connected to -Rx (Pin
11) , the Rx- is connected to the -Tx (Pin 12) and the Rx+ is connected to the +Tx (Pin 13). The
shield connection for the RS422 cable should be connected to the power supply ground Gnd (Pin
19)
3.4.2 RS485 Multi-Drop 2 wire connection half duplex.
The LDU series can be wired in a multi-drop mode where up to 32 devices can be connected to one
bus. The +Rx (Pin 10) and +Tx (pin 13) should be commoned together and should be connected to
the A (Tx-/Rx- or D-) terminal of the host RS485 interface. The -Rx (Pin 11) and the -Tx (Pin 12)
should similarly be commoned and connected to the B (Tx+/Rx+ or D+) terminal of the host RS485
interface. The ground connection (GND) from the host RS485 should be connected to the power
supply ground of the LDUs. Termination resistors of 120 Ohm each should be placed between the B
(Tx+/Rx+ or D+) and A (Tx-/Rx- or D-) lines at host end of the bus and between the B (Tx+/Rx+ or
D+) and the A (Tx-/Rx- or D-) lines of the last device on the bus. In addition it may be necessary to
add pull up and pull down resistors (R1 & R2) to the B (Tx+/Rx+ or D+) and A (Tx-/Rx- or D-) lines to
prevent these lines ‘floating’ during periods of no transmission. Where the supply voltage to the
RS485 line driver IC is typically 5V DC for example, the value of R1 & R2 can be 470 Ohms each.
Where for example you are using a RS232 to RS485 converter with a supply voltage of 12 V DC,
the value of R1 & R2 should be increased to 1K2 Ohms (1200 Ohms).
The LDU 68.x have 2 logic inputs on pins 14 & 16 and 2 logic outputs (Open Collector) on pins 15 &
17. The common for both the logic inputs and outputs is internally connected to the ground of the
power supply so no separate common supply is required. Control signals (10 - 30 V DC) applied to
the logic inputs can be used to trigger a variety of weighing processes such as check-weighing,
filling etc. The status of the logic inputs can be read via the LDU 68.x communication port. The logic
outputs are effectively weight dependant switches. These can be used to control alarms or filling
valves etc. The load to be controlled is wired between the positive supply and the appropriate logic
output terminal on the LDU 68.x.
Issue 1h
B or D+ or Tx+/Rx+
Gnd
A or D- or Tx-/Rx-
Vcc
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Inp 3
2
Gnd
NC
Sen
0
+Pwr
Out
Rx
+
Tx
+
In
0
In
1
Rx
-
Tx
-
0
Out
1
1
Inp4
Sen5
Exc6
Gnd7
NC8
9
12
13
11
10
15
14
17
16
19
18
+
+
-
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
Exc
Gnd
TECHNIQUES LIMITED
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Sw2
Sw1
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 8 LDU68 Series Manual
The LDU 68 can also be wired in a 4 wire multi-drop mode where up to 32 devices can be
connected to one bus. To achieve this simply parallel up all connections. So all Rx + terminals are
connected together and are connected to the Tx+ terminal of the host RS485 interface. All Rx -
terminals are connected together and connected to the Tx -terminal of the host RS485 interface. All
Tx + terminals are connected together and are connected to the Rx+ terminal of the host RS485
interface. All Tx- terminals are connected together and connected to the Rx- terminal of the host
RS485 interface. All ground connections are connected together and connected to ground
connection on the host RS485. Terminating resistors (120 Ohms each) should be connected across
each pair of wires both at the host end and on the last device on the bus.
3.4.3 RS485 4 Wire Multi-drop Connections Half Duplex (Recommended)
Gnd
Tx+
Rx+
RS485 Interface
Vcc
Tx-
Rx-
Terminators - 120 Ohm Each
Terminators - 120 Ohm Each
R1
R2
P2
P1
Span Adj. Made in EU
Zero Adj.
R3
R4
Made in EU F1
Buss
400mA
R2
P2 Span Adj.
R1
P1
Zero Adj.
R3
R4
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
R1
R2
P2
P1
Span Adj. Made in EU
Zero Adj.
R3
R4
Made in EU F1
Buss
400mA
R2
P2 Span Adj.
R1
P1
Zero Adj.
R3
R4
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 9 LDU 68 Series Manual
This page is intentionally left blank
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 8 LDU68 Series Manual
The LDU 68 can also be wired in a 4 wire multi-drop mode where up to 32 devices can be
connected to one bus. To achieve this simply parallel up all connections. So all Rx + terminals are
connected together and are connected to the Tx+ terminal of the host RS485 interface. All Rx -
terminals are connected together and connected to the Tx -terminal of the host RS485 interface. All
Tx + terminals are connected together and are connected to the Rx+ terminal of the host RS485
interface. All Tx- terminals are connected together and connected to the Rx- terminal of the host
RS485 interface. All ground connections are connected together and connected to ground
connection on the host RS485. Terminating resistors (120 Ohms each) should be connected across
each pair of wires both at the host end and on the last device on the bus.
3.4.3 RS485 4 Wire Multi-drop Connections Half Duplex (Recommended)
Gnd
Tx+
Rx+
RS485 Interface
Vcc
Tx-
Rx-
Terminators - 120 Ohm Each
Terminators - 120 Ohm Each
R1
R2
P2
P1
Span Adj. Made in EU
Zero Adj.
R3
R4
Made in EU F1
Buss
400mA
R2
P2 Span Adj.
R1
P1
Zero Adj.
R3
R4
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
R1
R2
P2
P1
Span Adj. Made in EU
Zero Adj.
R3
R4
Made in EU F1
Buss
400mA
R2
P2 Span Adj.
R1
P1
Zero Adj.
R3
R4
Exc 6
7
Gnd
Gnd
Gnd
9
Pwr
Out
In
Out
In
Tx
Tx
Rx
Rx
+
+
0
1
-
-
0
1
8
Sen5
Inp4
Inp3
Sen2
Exc1
0
16
17
19
18
15
14
13
12
11
10
+
+
+
-
-
-
I I I
Load Cell Digitising Unit
LDU 68.1
Cert.no. DK0199 - R76 - 10.04
nmax = 10000
-15°C/+55°C
CE
Dmin = 1.0mV/VSI
NC
NC
TECHNIQUES LIMITED
www.sensortechniques.com
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 9 LDU 68 Series Manual
This page is intentionally left blank
Issue 1h
Network address
Get/Set Setpoint n action
Calibrate Enable - TAC Code
Calibrate Gain (TAC protected)
Close ‘Open’ devices (RS485 Multi-drop)
Calibrate Maximum (TAC protected)
Calibrate Save
Calibrate Zero
Short Description
Display Step Size
Factory Default
Get Average Weight
Usage
Read or Change Setpoint Action
Read or Set the Network Address
Read or Change the Baud Rate
Allows access to important Cal/Set up parameters
Calibrate the weighing system span or gain
Closes all open communication pathes (Multi-drop)
Read or modify the maximum output value
Save Calibration Parameters to EEPROM(TAC protected)
Calibrate the weighing system zero
Read or modify the decimal point position
(TAC protected)
(TAC protected)
(TAC protected) Read or modify the display step size or increment
Select half (0) or full (1) duplex
Reset to factory default settings
Define time over which a rolling average is calculated
Read or modify the filter mode
Read or modify the filter level (strength)
Get the current ‘average’ weight value
Parameter Values
0 to 255
0 to 1
9,600 to 115,200
0 to 65,535
0 to 99,999
None
0 to 99,999
None
None
0 to 5
1 to 200
0 to 1
None
0 to 15
0 = IIR Filter / 1= FIR Filter
0 to 8
None
Full Description on
Page 32
Page 31
Page 32
Page 18
Page 19
Page 32
Page 18
Page 20 & 34
Page 19
Page 19
Page 18
Page 32
Page 20
Page 22
Page 22
Page 22
Page 16 & 26
AD
An
BR
CE
CG
CL
CM
CS
CZ
DP
DS
DX
FD
FF
FM
FL
GA
Baud Rate
Command
Decimal Point
Duplex
Filter Factor
Filter Mode
Filter Level
Get Filtered Weight Value Get the filtered net weight value None Page 25
GF
Get Gross Weight Value Get the gross weight value. None Page 25
GG
Get Image Get EEPROM Image as an Intel hexfile None Page 34
GI
Get Net Weight Value
Get Sample (ADC value)
Get the net weight value
Get the ADC sample value.
None
None
Page 25
Page 25
GN
GS
Get Tare Value Get the tare value None Page 25
GT
Get ‘Long’ Weight Get the ‘Long’ weight value None Page 25
GW
Get/Set Hysteresis on Setpoint n
Get Device Identity
Get Device Status
Read/Modify Output Status
Get Firmware Version Number
Read Status of Inputs
Read/Modify Control of Outputs
Read or modify the hysteresis value on Setpoint n
Read the device identity
Read or modify the control of the logic outputs
Read the status of the logic inputs
Read or modify the status of the logic outputs
Get the device status.
Get the firmware version number
-99,999 to 99,999
None
0000 to 0011
None
0000 to 0011
None
None
Page 30
Page 13
Page 29
Page 28
Page 28
Page 13
Page 13
Measuring Time The time over which the average value is derived 0 to 500 ms
No-motion Range Read or modify the no-motion range
No-motion Time Read or modify the no-motion time in msecs
0 to 65,535
0 to 65,535
Page 15
Page 21
Page 21
Hn
ID
IM
IN
IO
IS
IV
MT
NR
NT
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 10 LDU 68 Series Manual
4 COMMANDS OVERVIEW
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 11 LDU 68 Series Manual
4 COMMANDS OVERVIEW (Continued)
ZT Zero track (TAC protected) Zero track off (0) or zero track on (1 ... 255) 0 to 255 Page 19
ZI Initial Zero (TAC protected) Set the initial zero range 0 to 99,999 Page 20
Short DescriptionCommand Usage
RZ Reset system zero Restores the calibration zero point None Page 23
WT Read or modify the warm up delay time Read or modify the warm up time delay 0 to 255
Page 16 & 27
SA Start auto transmitting average value Start auto transmitting the average weight value None
SD
SF
SG
SN
Sn
SR
SS
ST
SW
Start Delay
Start auto transmitting filtered value
Start auto transmitting gross weight
Start auto transmitting ‘Long’ weight value
Start auto transmitting net weight
Get/Set the setpoint values
Software reset
Set Tare
Read or set the delay between trigger & measurement
Start auto transmitting the filtered weight value
Start auto transmitting the gross weight value
Start auto transmitting the net weight value
Start auto transmitting the ‘Long’ weight value
Read or modify the setpoint values
Causes the LDU to perform a software reset
Save Setpoint Parameters to EEPROM
Sets the tare value and puts the LDU in net mode
Save Setpoint Parameters
0 to 500 ms
None
None
None
-99,999 to +99,999
None
None
None
None
Page 15
Page 27
Page 27
Page 27
Page 30
Page 14
Page 34
Page 24
Page 27
SZ Set Zero Set a new system zero None Page 23
TD Transmit Delay Set delay between receiving a command & responding 0 to 255 Page 33
TE
TL
TR
UR
WP
Trigger Edge
Trigger Level
Trigger
Read or modify the update rate
Save setup parameters
Selects trigger on a falling (0) or rising edge(1)
Set the trigger level at which measurement cycle starts
Software trigger to start measurement cycle
Read or modify the update rate
Save setup parameters to EEPROM
0 or 1
0 to 99,999
None
0 to 7
None
Page 15
Page 15
Page 16
Page 22
Page 34
Page ?
Cancels tare value - unit reverts to Gross weighing None Page 24
RT Reset Tare
Parameter Values Full Description on
Please note that commands which are greyed out are not available on this model
Open connection Open a connection to device number x 0 to 255 Page 33OP
Put EEPROM Image Put EEPROM Image as a Intel hexfile None Page 34PI
Issue 1h
Network address
Get/Set Setpoint n action
Calibrate Enable - TAC Code
Calibrate Gain (TAC protected)
Close ‘Open’ devices (RS485 Multi-drop)
Calibrate Maximum (TAC protected)
Calibrate Save
Calibrate Zero
Short Description
Display Step Size
Factory Default
Get Average Weight
Usage
Read or Change Setpoint Action
Read or Set the Network Address
Read or Change the Baud Rate
Allows access to important Cal/Set up parameters
Calibrate the weighing system span or gain
Closes all open communication pathes (Multi-drop)
Read or modify the maximum output value
Save Calibration Parameters to EEPROM(TAC protected)
Calibrate the weighing system zero
Read or modify the decimal point position
(TAC protected)
(TAC protected)
(TAC protected) Read or modify the display step size or increment
Select half (0) or full (1) duplex
Reset to factory default settings
Define time over which a rolling average is calculated
Read or modify the filter mode
Read or modify the filter level (strength)
Get the current ‘average’ weight value
Parameter Values
0 to 255
0 to 1
9,600 to 115,200
0 to 65,535
0 to 99,999
None
0 to 99,999
None
None
0 to 5
1 to 200
0 to 1
None
0 to 15
0 = IIR Filter / 1= FIR Filter
0 to 8
None
Full Description on
Page 32
Page 31
Page 32
Page 18
Page 19
Page 32
Page 18
Page 20 & 34
Page 19
Page 19
Page 18
Page 32
Page 20
Page 22
Page 22
Page 22
Page 16 & 26
AD
An
BR
CE
CG
CL
CM
CS
CZ
DP
DS
DX
FD
FF
FM
FL
GA
Baud Rate
Command
Decimal Point
Duplex
Filter Factor
Filter Mode
Filter Level
Get Filtered Weight Value Get the filtered net weight value None Page 25
GF
Get Gross Weight Value Get the gross weight value. None Page 25
GG
Get Image Get EEPROM Image as an Intel hexfile None Page 34
GI
Get Net Weight Value
Get Sample (ADC value)
Get the net weight value
Get the ADC sample value.
None
None
Page 25
Page 25
GN
GS
Get Tare Value Get the tare value None Page 25
GT
Get ‘Long’ Weight Get the ‘Long’ weight value None Page 25
GW
Get/Set Hysteresis on Setpoint n
Get Device Identity
Get Device Status
Read/Modify Output Status
Get Firmware Version Number
Read Status of Inputs
Read/Modify Control of Outputs
Read or modify the hysteresis value on Setpoint n
Read the device identity
Read or modify the control of the logic outputs
Read the status of the logic inputs
Read or modify the status of the logic outputs
Get the device status.
Get the firmware version number
-99,999 to 99,999
None
0000 to 0011
None
0000 to 0011
None
None
Page 30
Page 13
Page 29
Page 28
Page 28
Page 13
Page 13
Measuring Time The time over which the average value is derived 0 to 500 ms
No-motion Range Read or modify the no-motion range
No-motion Time Read or modify the no-motion time in msecs
0 to 65,535
0 to 65,535
Page 15
Page 21
Page 21
Hn
ID
IM
IN
IO
IS
IV
MT
NR
NT
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 10 LDU 68 Series Manual
4 COMMANDS OVERVIEW
Issue 1h
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 11 LDU 68 Series Manual
4 COMMANDS OVERVIEW (Continued)
ZT Zero track (TAC protected) Zero track off (0) or zero track on (1 ... 255) 0 to 255 Page 19
ZI Initial Zero (TAC protected) Set the initial zero range 0 to 99,999 Page 20
Short DescriptionCommand Usage
RZ Reset system zero Restores the calibration zero point None Page 23
WT Read or modify the warm up delay time Read or modify the warm up time delay 0 to 255
Page 16 & 27
SA Start auto transmitting average value Start auto transmitting the average weight value None
SD
SF
SG
SN
Sn
SR
SS
ST
SW
Start Delay
Start auto transmitting filtered value
Start auto transmitting gross weight
Start auto transmitting ‘Long’ weight value
Start auto transmitting net weight
Get/Set the setpoint values
Software reset
Set Tare
Read or set the delay between trigger & measurement
Start auto transmitting the filtered weight value
Start auto transmitting the gross weight value
Start auto transmitting the net weight value
Start auto transmitting the ‘Long’ weight value
Read or modify the setpoint values
Causes the LDU to perform a software reset
Save Setpoint Parameters to EEPROM
Sets the tare value and puts the LDU in net mode
Save Setpoint Parameters
0 to 500 ms
None
None
None
-99,999 to +99,999
None
None
None
None
Page 15
Page 27
Page 27
Page 27
Page 30
Page 14
Page 34
Page 24
Page 27
SZ Set Zero Set a new system zero None Page 23
TD Transmit Delay Set delay between receiving a command & responding 0 to 255 Page 33
TE
TL
TR
UR
WP
Trigger Edge
Trigger Level
Trigger
Read or modify the update rate
Save setup parameters
Selects trigger on a falling (0) or rising edge(1)
Set the trigger level at which measurement cycle starts
Software trigger to start measurement cycle
Read or modify the update rate
Save setup parameters to EEPROM
0 or 1
0 to 99,999
None
0 to 7
None
Page 15
Page 15
Page 16
Page 22
Page 34
Page ?
Cancels tare value - unit reverts to Gross weighing None Page 24
RT Reset Tare
Parameter Values Full Description on
Please note that commands which are greyed out are not available on this model
Open connection Open a connection to device number x 0 to 255 Page 33OP
Put EEPROM Image Put EEPROM Image as a Intel hexfile None Page 34PI
Issue 1h
5 COMMANDS
Ideas in Measuring ..
TECHNIQUES LIMITED
Page 12 LDU 68 Series Manual
For better clarity, all commands are divided into groups as described on the following pages.
5.1 System diagnostic Commands - ID, IV, IS, SR 13
5.2 Checkweigher Commands - SD, MT, TE, TL, TR, GA, SA 15
5.3 Calibration Commands - CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI 18
5.4 Motion detection Commands - NR, NT 21
5.5 Filter setting Commands - FL, FF, UR 22
5.6 Set Zero/Tare and Reset Zero/Tare Commands - SZ, RZ, ST, RT 23
5.7 Output Commands - GG, GN, GT, GS, GF, GW, GA 25
5.8 Auto-transmit Commands - SG, SN, SF, SW, SA 27
5.9 Commands for external I/O control - IN, IO, IM 28
5.10 Setpoint Commands - Sn, Hn, An 30
5.11 Communication setup Commands - AD, CL, BR, DX, OP, TD 32
5.12 Save calibration, setup & setpoint parameters Commands - CS, WP, SS, PI, GI 34
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Use these commands to get the LDU XX.X type, firmware version or device status. These
commands are sent without parameters.
Leftmost 3-digit value: Rightmost 3-digit value:
1 Signal stable 1 (not used)
2 Zero action performed 2 (not used)
4 Tare active 4 (not used)
8 (not used) 8 (not used)
16 (not used) 16 (not used)
32 (not used) 32 (not used)
64 Output 0 active 64 (not used)
128 Output 1 active 128 (not used)
IS Request device status
Master (PC / PLC) sends
IS S:067000 (example)
LDU XX.X responds
The response to this request comprises of two 3-digit decimal values, which can be decoded
according to the table below:
For example the result S:067000 decodes as follows:
Signal Stable (no-motion) 1
Zero action 2
Output 0 active 64
Total 67
Please note that the bits that are not used are set to zero.
Master (PC / PLC) sends
IV V:0300
LDU XX.X responds
The response to this request gives the firmware version of the active device.
IV Request of firmware version
ID Request of device identity
Master (PC / PLC) sends
ID D:6810
LDU XX.X responds
The response to this request gives the actual identity of the active device. This is particularly useful
when trying to identify different device types on a bus.
5.1 System diagnosis Commands – ID, IV, IS, SR
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For better clarity, all commands are divided into groups as described on the following pages.
5.1 System diagnostic Commands - ID, IV, IS, SR 13
5.2 Checkweigher Commands - SD, MT, TE, TL, TR, GA, SA 15
5.3 Calibration Commands - CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI 18
5.4 Motion detection Commands - NR, NT 21
5.5 Filter setting Commands - FL, FF, UR 22
5.6 Set Zero/Tare and Reset Zero/Tare Commands - SZ, RZ, ST, RT 23
5.7 Output Commands - GG, GN, GT, GS, GF, GW, GA 25
5.8 Auto-transmit Commands - SG, SN, SF, SW, SA 27
5.9 Commands for external I/O control - IN, IO, IM 28
5.10 Setpoint Commands - Sn, Hn, An 30
5.11 Communication setup Commands - AD, CL, BR, DX, OP, TD 32
5.12 Save calibration, setup & setpoint parameters Commands - CS, WP, SS, PI, GI 34
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Use these commands to get the LDU XX.X type, firmware version or device status. These
commands are sent without parameters.
Leftmost 3-digit value: Rightmost 3-digit value:
1 Signal stable 1 (not used)
2 Zero action performed 2 (not used)
4 Tare active 4 (not used)
8 (not used) 8 (not used)
16 (not used) 16 (not used)
32 (not used) 32 (not used)
64 Output 0 active 64 (not used)
128 Output 1 active 128 (not used)
IS Request device status
Master (PC / PLC) sends
IS S:067000 (example)
LDU XX.X responds
The response to this request comprises of two 3-digit decimal values, which can be decoded
according to the table below:
For example the result S:067000 decodes as follows:
Signal Stable (no-motion) 1
Zero action 2
Output 0 active 64
Total 67
Please note that the bits that are not used are set to zero.
Master (PC / PLC) sends
IV V:0300
LDU XX.X responds
The response to this request gives the firmware version of the active device.
IV Request of firmware version
ID Request of device identity
Master (PC / PLC) sends
ID D:6810
LDU XX.X responds
The response to this request gives the actual identity of the active device. This is particularly useful
when trying to identify different device types on a bus.
5.1 System diagnosis Commands – ID, IV, IS, SR
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SR Software Reset
This command will respond with ‘OK’ and after a maximum of 400 ms perform a complete reset of
the LDU. This has the same functionality as powering off and on again (hardware reset).
Master (PC / PLC) sends
SR OK
LDU XX.X responds
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5.2 Check Weigher Set up Commands SD, MT, GA, TE, TR, TL
Note: All setups should be stored with the WP command before power off.
Set the delay (in milliseconds) between the falling or rising edge of the trigger pulse and the start of
the measurement cycle. Permitted values are 0 ... 500 ms. Factory default setting SD = 0 [Start
Delay = 0 ms]. To check the current setting issue the command without any additional parameters.
To change the setting issue the command with the additional parameter. See table below.
See check weighing timing diagram on page 17
SD Start Delay 0 ... 500 milliseconds
Master (PC / PLC) sends LDU XX.X responds Result
SD
SD_200
S+00100
OK
Start Delay set to 100 milliseconds
Start Delay changed to 200 milliseconds
Please note that if MT = 0 then the trigger and average functions are disabled. The factory default
setting MT=0 [Measuring Time = 0]. See check weighing timing diagram on page 17
Set the time (in milliseconds) during which the weight average will be calculated. Permitted values
are 0 ... 500 milliseconds. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter. See table
below. See table below.
MT Measuring Time. Range 0 ... 500 milliseconds
Master (PC / PLC) sends LDU XX.X responds Result
MT
MT_200
M+00100
OK
Measuring Time set to 100 milliseconds
Measuring Time changed to 200 msecs
Using the TE command you can select whether the measuring cycle is triggered on a rising or
falling edge. Permitted values are 0 [Falling Edge] or 1 [Rising Edge]. Factory default setting TE =
0 [Falling Edge]. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter.
TE Trigger Edge
See check weighing timing diagram on page 17
Master (PC / PLC) sends LDU XX.X responds Result
TE
TE_0
E:001
OK
Trigger Edge set on a rising edge
Trigger Edge changed to a falling edge
This command sets the trigger level above or below which (depending if the Trigger Edge TE is set
to a rising or falling edge) the measuring cycle starts. Permitted values 0 ... 99999. Factory default
setting TL = 99999. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter. See table
below. (TL continues over the page.)
TL Trigger Level
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SR Software Reset
This command will respond with ‘OK’ and after a maximum of 400 ms perform a complete reset of
the LDU. This has the same functionality as powering off and on again (hardware reset).
Master (PC / PLC) sends
SR OK
LDU XX.X responds
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5.2 Check Weigher Set up Commands SD, MT, GA, TE, TR, TL
Note: All setups should be stored with the WP command before power off.
Set the delay (in milliseconds) between the falling or rising edge of the trigger pulse and the start of
the measurement cycle. Permitted values are 0 ... 500 ms. Factory default setting SD = 0 [Start
Delay = 0 ms]. To check the current setting issue the command without any additional parameters.
To change the setting issue the command with the additional parameter. See table below.
See check weighing timing diagram on page 17
SD Start Delay 0 ... 500 milliseconds
Master (PC / PLC) sends LDU XX.X responds Result
SD
SD_200
S+00100
OK
Start Delay set to 100 milliseconds
Start Delay changed to 200 milliseconds
Please note that if MT = 0 then the trigger and average functions are disabled. The factory default
setting MT=0 [Measuring Time = 0]. See check weighing timing diagram on page 17
Set the time (in milliseconds) during which the weight average will be calculated. Permitted values
are 0 ... 500 milliseconds. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter. See table
below. See table below.
MT Measuring Time. Range 0 ... 500 milliseconds
Master (PC / PLC) sends LDU XX.X responds Result
MT
MT_200
M+00100
OK
Measuring Time set to 100 milliseconds
Measuring Time changed to 200 msecs
Using the TE command you can select whether the measuring cycle is triggered on a rising or
falling edge. Permitted values are 0 [Falling Edge] or 1 [Rising Edge]. Factory default setting TE =
0 [Falling Edge]. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter.
TE Trigger Edge
See check weighing timing diagram on page 17
Master (PC / PLC) sends LDU XX.X responds Result
TE
TE_0
E:001
OK
Trigger Edge set on a rising edge
Trigger Edge changed to a falling edge
This command sets the trigger level above or below which (depending if the Trigger Edge TE is set
to a rising or falling edge) the measuring cycle starts. Permitted values 0 ... 99999. Factory default
setting TL = 99999. To check the current setting issue the command without any additional
parameters. To change the setting issue the command with the additional parameter. See table
below. (TL continues over the page.)
TL Trigger Level
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See check weighing timing diagram on page 17
This command will start the measuring cycle immediately in the same way as the hardware trigger.
The average value (see GA below) will be calculated over the Measuring Time (MT) after a Start
Delay (SD). The GA value is only updated after a new measuring cycle has been completed.
TR Trigger
Master (PC / PLC) sends LDU XX.X responds Result
TR OK Measuring cycle triggered
See check weighing timing diagram on page 17
Please note that during the period after the measuring cycle has been triggered but before the
value of GA has been updated, the GA command will return a value 99999
Issuing the GA command, the LDU returns the current weight average calculated over the
Measuring Time MT. The GA value is only updated after another measuring cycle is completed. the
format of the response includes any decimal places etc. which may have been set.
GA Get Average
Master (PC / PLC) sends LDU XX.X responds Result
GA A+01.100 Weight average (over time MT) GA = 1.100g
Master (PC / PLC) sends LDU XX.X responds Result
TL
TL_1000
T+99999
OK
Trigger Level set to 99,999 divisions
Trigger Level changed to 1,000 divisions
See check weighing timing diagram on page 17
TL Trigger Level (Continued)
Please note that during the period after the measuring cycle has been triggered but before the
value of SA has been updated, the SA command will return a value 99999
This command sends the ‘average’ weight value continuously. The SA command is issued without
any parameters and the LDU returns the current weight average calculated over the Measuring
Time MT. The SA value is only updated after another measuring cycle is completed. The format of
the response includes any decimal places etc. which may have been set.
SA Send the ‘Average’ weight value continuously
Master (PC / PLC) sends LDU XX.X responds Result
SA A+01.100 Weight average (over time MT) SA = 1.100g
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Weight (g)
Time (ms)
trigger point
Timing Control Diagram
MT
SD
(Measuring Time)
(Start Delay)
TL
(Trigger Level)
TE
(Trigger Edge)
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See check weighing timing diagram on page 17
This command will start the measuring cycle immediately in the same way as the hardware trigger.
The average value (see GA below) will be calculated over the Measuring Time (MT) after a Start
Delay (SD). The GA value is only updated after a new measuring cycle has been completed.
TR Trigger
Master (PC / PLC) sends LDU XX.X responds Result
TR OK Measuring cycle triggered
See check weighing timing diagram on page 17
Please note that during the period after the measuring cycle has been triggered but before the
value of GA has been updated, the GA command will return a value 99999
Issuing the GA command, the LDU returns the current weight average calculated over the
Measuring Time MT. The GA value is only updated after another measuring cycle is completed. the
format of the response includes any decimal places etc. which may have been set.
GA Get Average
Master (PC / PLC) sends LDU XX.X responds Result
GA A+01.100 Weight average (over time MT) GA = 1.100g
Master (PC / PLC) sends LDU XX.X responds Result
TL
TL_1000
T+99999
OK
Trigger Level set to 99,999 divisions
Trigger Level changed to 1,000 divisions
See check weighing timing diagram on page 17
TL Trigger Level (Continued)
Please note that during the period after the measuring cycle has been triggered but before the
value of SA has been updated, the SA command will return a value 99999
This command sends the ‘average’ weight value continuously. The SA command is issued without
any parameters and the LDU returns the current weight average calculated over the Measuring
Time MT. The SA value is only updated after another measuring cycle is completed. The format of
the response includes any decimal places etc. which may have been set.
SA Send the ‘Average’ weight value continuously
Master (PC / PLC) sends LDU XX.X responds Result
SA A+01.100 Weight average (over time MT) SA = 1.100g
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Weight (g)
Time (ms)
trigger point
Timing Control Diagram
MT
SD
(Measuring Time)
(Start Delay)
TL
(Trigger Level)
TE
(Trigger Edge)
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5.3 Calibration Commands CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI
Note: TAC represents the Traceable Access Code (calibration counter) which
increments every time new calibration data is stored. Calibration values are only
stored in EEPROM when the CS command is issued (see CS command Page 15)
With this command you can either read the current TAC value or enable a calibration command. To
check the current TAC value issue the command without any additional parameters. To enable a
calibration command, issue the CE command with the current TAC value. See table below.
This command MUST be issued PRIOR to any attempt to change calibration parameters
such as CZ, CG etc. In legal for trade applications the TAC value can be used to check if any
critical parameters have been changed without re-verification. After each calibration the TAC
counter increases by 1.
CE TAC counter reading
Master (PC / PLC) sends LDU XX.X responds Result
CE
CE_17
E+00017 (example)
OK
Current TAC value is 17
Calibration commands enabled
This command sets the maximum output value. Permitted values are between 1 and 99999.
Factory default value CM = 99999. To check the current value issue the CM command without any
additional parameters. To change the value of CM, issue the CE command with the current TAC
value and then CM and the new setting. See table below.
The value of CM will determine the point at which the output will change to “oooooo” signifying
over-range.
Please note that the Set Zero (SZ) and the automatic Zero Track (ZT) functions are limited to ± 2 %
of the CM value.
CM Set maximum output value
Master (PC / PLC) sends LDU XX.X responds Result
CE
CM
CM_50000
CE_17
E+00017 (example)
M+30000
OK
OK
Current TAC value is 17
Current output maximum is set to 30,000
Output maximum changed to 50,000
Calibration commands enabled
This command allows you to set different output reading step sizes. Permitted values are 1, 2, 5,
10, 20, 50, 100, and 200. Factory default value DS = 1. For example, if the step size is set to 2,
then the output value will go up or down in 2s. To check the current step size, issue the DS
command without any additional parameters. To change the value of DS, issue the CE command
with the current TAC value and then DS and the new setting. See table below.
DS Set output reading step size
Master (PC / PLC) sends LDU XX.X responds Result
CE
DS
DS_50
CE_17
E+00017 (example)
S+00002
OK
OK
Current TAC value is 17
Display step size is set to 2
Display step size changed to 50
Calibration commands enabled
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This command allows the decimal point to be positioned anywhere between the most and least
significant digits. To check the current position, issue the DP command without any additional
parameters. To change the decimal point position, issue the CE command with the current TAC
value and then DP and the new setting. See table below.
DP Set decimal point position
Master (PC / PLC) sends LDU XX.X responds Result
CE
DP
DP_0
CE_17
E+00017 (example)
P+00002
OK
OK
Current TAC value is 17
Decimal point is set to 2 places (xxx.xx)
Decimal point set to no places (xxxxx)
Calibration commands enabled
For the best system performance, calibrate the gain (span) as near to the display maximum (CM)
as possible. A minimum calibration load of at least 20% is recommended. Factory default
calibration gain setting 20000 counts = 2.0000 mV/V input signal. Permitted values 0 - 99999
This command sets the calibration span or gain which is a reference point for all weight
calculations (TAC protected).To check the current gain calibration value, issue the CG command
without any additional parameters. To change the calibration gain value, issue the CE command
with the current TAC value and then CG (with the equivalent load applied). See table below.
CG Set calibration gain (Span)
Master (PC / PLC) sends LDU XX.X responds Result
CE
CG
CG_15000
CE_17
E+00017 (example)
G+10000
OK
OK
Current TAC value is 17
Calibration gain set at 10000 counts
Calibration gain set to15000 counts
Calibration commands enabled
This command sets the calibration zero point which is a reference point for all weight calculations
(TAC protected). To set a new calibration zero, issue the CE command with the current TAC value
and then CZ (when there is no load applied). See table below. Factory default ~ 0mV/V input signal
CZ Set the calibration zero point
Master (PC / PLC) sends LDU XX.X responds Result
CE E+00017 (example) Current TAC value is 17
CE_17 OK Calibration commands enabled
CZ OK New zero point saved
ZT continues over ....
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This command sets the zero tracking band in divisions. To check the current zero tracking band,
issue the ZT command without any additional parameters. To change the zero tracking band, issue
the CE command with the current TAC value and then ZT followed by the new setting.
ZT Zero tracking band
Master (PC / PLC) sends LDU XX.X responds Result
CE
ZT
ZT_2
CE_17
E+00017 (example)
Z+00001
OK
OK
Current TAC value is 17
Zero tracking band ± 1 divisions
Zero tracking band changed to ± 2 division
Calibration commands enabled
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5.3 Calibration Commands CE, CM, DS, DP, CZ, CG, ZT, FD, CS, ZI
Note: TAC represents the Traceable Access Code (calibration counter) which
increments every time new calibration data is stored. Calibration values are only
stored in EEPROM when the CS command is issued (see CS command Page 15)
With this command you can either read the current TAC value or enable a calibration command. To
check the current TAC value issue the command without any additional parameters. To enable a
calibration command, issue the CE command with the current TAC value. See table below.
This command MUST be issued PRIOR to any attempt to change calibration parameters
such as CZ, CG etc. In legal for trade applications the TAC value can be used to check if any
critical parameters have been changed without re-verification. After each calibration the TAC
counter increases by 1.
CE TAC counter reading
Master (PC / PLC) sends LDU XX.X responds Result
CE
CE_17
E+00017 (example)
OK
Current TAC value is 17
Calibration commands enabled
This command sets the maximum output value. Permitted values are between 1 and 99999.
Factory default value CM = 99999. To check the current value issue the CM command without any
additional parameters. To change the value of CM, issue the CE command with the current TAC
value and then CM and the new setting. See table below.
The value of CM will determine the point at which the output will change to “oooooo” signifying
over-range.
Please note that the Set Zero (SZ) and the automatic Zero Track (ZT) functions are limited to ± 2 %
of the CM value.
CM Set maximum output value
Master (PC / PLC) sends LDU XX.X responds Result
CE
CM
CM_50000
CE_17
E+00017 (example)
M+30000
OK
OK
Current TAC value is 17
Current output maximum is set to 30,000
Output maximum changed to 50,000
Calibration commands enabled
This command allows you to set different output reading step sizes. Permitted values are 1, 2, 5,
10, 20, 50, 100, and 200. Factory default value DS = 1. For example, if the step size is set to 2,
then the output value will go up or down in 2s. To check the current step size, issue the DS
command without any additional parameters. To change the value of DS, issue the CE command
with the current TAC value and then DS and the new setting. See table below.
DS Set output reading step size
Master (PC / PLC) sends LDU XX.X responds Result
CE
DS
DS_50
CE_17
E+00017 (example)
S+00002
OK
OK
Current TAC value is 17
Display step size is set to 2
Display step size changed to 50
Calibration commands enabled
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This command allows the decimal point to be positioned anywhere between the most and least
significant digits. To check the current position, issue the DP command without any additional
parameters. To change the decimal point position, issue the CE command with the current TAC
value and then DP and the new setting. See table below.
DP Set decimal point position
Master (PC / PLC) sends LDU XX.X responds Result
CE
DP
DP_0
CE_17
E+00017 (example)
P+00002
OK
OK
Current TAC value is 17
Decimal point is set to 2 places (xxx.xx)
Decimal point set to no places (xxxxx)
Calibration commands enabled
For the best system performance, calibrate the gain (span) as near to the display maximum (CM)
as possible. A minimum calibration load of at least 20% is recommended. Factory default
calibration gain setting 20000 counts = 2.0000 mV/V input signal. Permitted values 0 - 99999
This command sets the calibration span or gain which is a reference point for all weight
calculations (TAC protected).To check the current gain calibration value, issue the CG command
without any additional parameters. To change the calibration gain value, issue the CE command
with the current TAC value and then CG (with the equivalent load applied). See table below.
CG Set calibration gain (Span)
Master (PC / PLC) sends LDU XX.X responds Result
CE
CG
CG_15000
CE_17
E+00017 (example)
G+10000
OK
OK
Current TAC value is 17
Calibration gain set at 10000 counts
Calibration gain set to15000 counts
Calibration commands enabled
This command sets the calibration zero point which is a reference point for all weight calculations
(TAC protected). To set a new calibration zero, issue the CE command with the current TAC value
and then CZ (when there is no load applied). See table below. Factory default ~ 0mV/V input signal
CZ Set the calibration zero point
Master (PC / PLC) sends LDU XX.X responds Result
CE E+00017 (example) Current TAC value is 17
CE_17 OK Calibration commands enabled
CZ OK New zero point saved
ZT continues over ....
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This command sets the zero tracking band in divisions. To check the current zero tracking band,
issue the ZT command without any additional parameters. To change the zero tracking band, issue
the CE command with the current TAC value and then ZT followed by the new setting.
ZT Zero tracking band
Master (PC / PLC) sends LDU XX.X responds Result
CE
ZT
ZT_2
CE_17
E+00017 (example)
Z+00001
OK
OK
Current TAC value is 17
Zero tracking band ± 1 divisions
Zero tracking band changed to ± 2 division
Calibration commands enabled
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ZT Zero tracking (continued)
This command restores the LDU back to the original factory settings. The data will be written back
into EEPROM and the TAC will be incremented by 1
Please note: All calibration and set up data will be lost if the FD command is issued !
FD Factory default settings
Master (PC / PLC) sends LDU XX.X responds Result
CE E+00017 (example) Current TAC value is 17
CE_17 OK Calibration commands enabled
FD OK Factory default settings restored
This command stores the calibration values in EEPROM and causes the TAC code to be
incremented by 1. If the CS command is not issued and the power to the LDU fails or is
turned off, all changes to the calibration values will be lost.
The CS command saves all calibration group values as set by CZ, CG, CM, DS, DP and ZT. To do
this issue the CE command with the current TAC code followed by CS.
CS Save the calibration values
Master (PC / PLC) sends LDU XX.X responds Result
CE E+00017 (example) Current TAC value is 17
CE_17 OK Calibration commands enabled
CS OK Calibration values stored
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Zero tracking will only be performed on values within the zero track band, at a rate of 0.4 d per
second where d = display set size (see DS command). The zero will only be tracked if it is within
the zero track range. See ZR command. If ZT is set to 0, zero tracking is turned off. Factory
default: ZT = 0.
This command sets an initial zero range on power up in divisions. If ZI is set to 0 (default value) an
initial zero on power up is not performed. If ZI is set to something other than zero, the device will
automatically perform a set zero on power up provided that the weight value is stable (within the
No motion parameters) and the zero is within the ZI range. To check the current value, issue the ZI
command without any additional parameters. To change the value, issue the CE command with the
current TAC value and then ZI followed by the new value. See table below.
ZI Initial Zero Range
Master (PC / PLC) sends LDU XX.X responds Result
CE
ZI
ZI_1
CE_17
E+00017 (example)
R+00005
OK
OK
Current TAC value is 17
Initial Zero range 5 divisions
Initial Zero range changed to 1division
Calibration commands enabled
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The motion detection facility prevents certain functions from being performed if the weight value is
unstable or ‘in-motion’.This ensures that a new value cannot be set when the weight value is
varying greatly over a short period of time. For a ‘no-motion’ or ‘stable’ condition to be achieved,
the weight signal must not vary by more than NR divisions over the time period NT. If the weight
signal is stable, the relevant bit of the ‘Info status’ (IS) response will be set.
The following functions are disabled if motion is detected:
Calibrate Zero (CZ), Calibrate Gain (CG), Set Zero (SZ) and Set Tare (ST)
5.4 Motion detection commands - NR, NT
This command sets the range within which the weight signal can vary and still be considered
‘stable’. Permitted values are between 0 and 65535. To check the current value, issue the NR
command without any additional parameters. To change the value of NR, issue the NR command
with the new setting. See table below. To save this change to EEPROM use the WP command.
With NR = 2, the weight signal can vary no more than ± 2 d, in the time period NT in order to be
considered stable. Factory default : NR =1
NR No motion range
Master (PC / PLC) sends LDU XX.X responds Result
NR R+00010 No motion range set to 10 d
NR_2 OK No motion range changed to 2 d
WP OK Write parameter to EEPROM
This command sets the time (in milliseconds) over which the weight signal is checked to see if it is
‘stable’ or has ‘no-motion’. The weight signal has to vary by less than NR divisions over the time
period NT, to be considered ‘stable’. Permitted values are between 0 and 65535. To check the
current value, issue the NT command without any additional parameters. To change the value of
NT, issue the NT command with the new setting. See table below. To save this change to EEPROM
use the WP command.
With NT = 500, the weight signal can vary no more than ± NR divisions, in the 500 ms in order to
be considered stable. Factory default : NT = 1000 milliseconds.
NT No motion time
Master (PC / PLC) sends LDU XX.X responds Result
NT T+01000 No motion time set to 1000 ms
NT_500 OK No motion time changed to 500 ms
WP OK Write parameter to EEPROM
Issue 1h
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