FMS EMGZ621A User manual

Operating Manual EMGZ621A
Digital microprocessor controlled
Double Channel Tension Measuring Amplifier
Version 1.12 02/2007 ff
Firmware Version: ab 2.01
GSD Version ab 1.00
Hardware Rev. D
This operation manual is also available in German.
Please contact your local representative.
Diese Bedienungsanleitung ist auch in Deutsch erhältlich.
Bitte kontaktieren Sie die Vertretung im zuständigen Land.
© by FMS Force Measuring Systems AG, CH-8154 Oberglatt – All rights reserved.

Operating Manual EMGZ621A
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1Safety Instructions
1.1 Description conditions
High danger of health
injury or loss of life Risk of damage
to machines Notice for
proper function
Danger
This symbol refers to high risk
for persons to get health injury
or loss life. It has to be
followed strictly.
Caution
This symbol refers to risk of
heavy mecanical damage.
This warning has to be
followed absolutely.
Note
This symbol refers to an
important information about
proper use. If not followed,
malfunction can be the
result.
1.2 List of safety instructions
Proper function of the electronic unit is only guaranteed with the recommended
application of the components. In case of other arrangement, heavy malfunction can be
the result. Therefore, the installation instructions on the following pages must be followed
strictly.
Local installation regulations are to preserve safety of electrical equipment. They are not
taken into consideration in this operating manual. However, they have to be followed strictly.
Bad earth connection may cause electric shock to persons, malfunction of the total system
or damage of the electronic unit! It is vital to ensure that proper earth connection is done.
The processor board is mounted to the housing cover. Improper handling may damage the
fragile electronic equipment! Don’t use rough tools such as screwdrivers or pliers! Touch
processor board as little as possible! Touch earthed metal part to discharge static
electricity before opening the housing!
Wrong setting of the jumpers and solder bridges may cause malfunction of the electronic
unit or the total system! Setting of the solder bridges and jumpers must be checked
carefully prior to power on! Setting of the solder bridges should be carried out by trained
personnel only!

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Table of Contents
1Safety Instructions ....................................................................................2
1.1 Description conditions 2
1.2 List of safety instructions 2
2Definitions..................................................................................................4
3System Components..................................................................................4
4System Description....................................................................................5
4.1 Functional Description 5
4.2 Force Sensors 5
4.3 Electronic Units EMGZ621A 6
5Quick Installation Guide..........................................................................7
6Dimensions.................................................................................................8
7Installation and Wiring ............................................................................9
7.1 Mounting the Electronic Unit 9
7.2 Wiring Diagram 11
7.3 Mounting the Force Sensors 12
8Operating .................................................................................................13
8.1 View of the Operating Panel 13
8.2 Configuring the Electronic Unit 14
8.3 Calibrating the Measuring Amplifier 15
8.4 Additional Settings 17
9Parametrization.......................................................................................18
9.1 Schematic Diagram of Parametrization 18
9.2 List of the system parameters 19
9.3 List of the parameters EMGZ621A 19
9.4 Description of the system parameters 20
9.5 Description of the Parameters EMGZ621A 21
9.6 Service Mode 25
10 Serial Interface (RS232) .........................................................................26
11 PROFIBUS Interface Description.........................................................27
11.1 Wiring of the PROFIBUS Data Cable 27
11.2 Setting the PROFIBUS Address 28
12 PROFIBUS Interface Description.........................................................29
12.1 GSD File 29
12.2 EMGZ621A DP Slave Functional Description 29
12.3 Initial Parameters 29
12.4 Configuration 30
12.5 Function Code 30
13 Interface CAN-Bus..................................................................................31
14 Interface DeviceNet.................................................................................31
15 Technical Reference................................................................................32
15.1 Additional Setting Elements 32
15.2 Dip-switch for the Analogue Inputs / Outputs 33
15.3 Technical Data 37
16 Trouble Shooting.....................................................................................38

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2Definitions
Offset: Correction value for compensation of the zero point difference. Thanks to the offset, it
is ensured that a force of 0N will generate a signal of zero exactly.
Gain: Amplification factor for the measuring signal. Use of an appropriate value will adjust
the force sensor signal to the tension feedback value exactly.
Strain gauge: Electronic component that will change its resistance while its length has
changed. Strain gauges are used in the FMS force sensors for acquisition of the feedback
value.
Subprint: Electronic extension module which can be plugged to the main board of the
electronic unit if required. That way, the possibilities of the electronic unit can be extended
easily.
3System Components
An EMGZ621A system consists of the following components (refer also to fig. 1):
Force sensors
•For mechanical/electrical conversion of the tension force
•Force measuring bearing
•Force measuring roller
•Force measuring journal
•Force measuring bearing block
Electronic unit EMGZ621A
•For supplying the force sensors and amplifying of the mV signal
•Two separated analogue inputs for the sensors of a single measuring point
•With operation panel for parametrization
•Digital inputs and outputs
•With robust aluminium housing
•Supports connection of external feedback displays
•Interface RS232
•Interface CAN-Bus, PROFIBUS, DeviceNet
(Variants and options in italic text)

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4System Description
fig. 1: Basic structure of the EMGZ621A Tension Measuring Amplifier E621A001e
4.1 Functional Description
The EMGZ621A is a double channel strain gauge amplifier for a single measuring point. The
material tension can be measured on both sides of the measuring roller independently.
The two force sensors of the measuring point measure the tension force in the material and
transmit the measuring values as mV signals to the electronic unit EMGZ621A. The electronic
unit amplifies the mV signals depending on configuration. The resulting feedback values are
shown in the display in [N] (lbs if required). In addition, the feedback values are provided at
the analogue outputs and various interfaces and can be evaluated by analog instruments, a
PLC or equivalent devices.
4.2 Force Sensors
The force sensors are based on the flexion beam principle. The flexion is measured by strain
gauges and transmitted to the electronic unit as mV signal. Due to the Wheatstone wiring of
the strain gauges, the measured value is depending also to the power supply. So, the force
sensors are supplied from the electronic unit by a very accurate power supply.

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4.3 Electronic Units EMGZ621A
Common
The electronic unit is mounted to a robust aluminium housing. It contains a microprocessor to
handle all calculations and communications, the highly accurate sensor power supply and the
signal amplifiers for the measuring values of one measuring point. The electronic unit has no
trimmers and only few jumpers to keep most accurate long-time and temperature stability.
Operation
The large backlit display with 2x16 characters, 4 LED’s and large keys guarantee simple
operation. All information is in plain text with the following languages selectable: English,
German, French and Italian. Most of the functions may be paramterized. The parametrization
can be done via the keys or the interfaces. All inputs are fail-safe stored in an EEPROM.
Additional settings can be made with jumpers or solder bridges.
Strain gauge amplifier
The strain gauge amplifier provides the highly accurate power supply (5VDC or 10VDC) for 1
force sensor per channel. The force sensors can be wired using 4 wire circuit or 6 wire circuit.
This allows accurate control of the bridge excitation even with very long cabling.
The power supply is equipped with current control. This allows to detect short circuit or cable
break automatically and to output an error message if required.
A highly accurate, fixed difference amplifier rises the mV signal up to 10V. This signal will be
fed to the A/D converter. The microprocessor then does all application specific calculations
with the digitized measuring value (such as offset, gain, lowpass filter, limit switches, etc).
The resulting feedback value is provided as both tension and current signal at the same time.
Using digital inputs, the amplifier can be switched easily between 2 different gain values (for
ex. to process different operating conditions). There is no reconfiguration required to switch
the gain values.
The strain gauge amplifier section written above is integrated twice to provide independent
evaluation of each force sensor.
Type Number of
channels Sensors per channel Feedback signals
EMGZ611 2 1 Difference A–B
Sum A+B
A
B
Interface
As an option, there are RS232, PROFIBUS, CAN-Bus or DeviceNet interfaces available.

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fig. 2: Block diagram of the electronic unit EMGZ621A E621A010e
5Quick Installation Guide
•Check all your requirements such as:
– configuration of the analogue inputs (power supply, 4 wire or 6 wire circuit)?
– configuration of the analogue outputs (signal level)?
– gain switching required?
– linking by interface etc.?
•Draw your final wiring diagram according to the wiring diagram (refer to „7.2 Wiring
diagram“)
•Install and wire all your components (refer to „7. Installation and wiring“)
•Parametrize and calibrate the measuring amplifier for each channel (refer to
„8. Operating“)
•Put system into operation; proceed a test run with low speed
•If required, do additional settings (refer to „8.4 Additional settings“)

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6Dimensions
fig. 3: Dimensions E611002e

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7Installation and Wiring
Caution
Proper function of the electronic unit is only guaranteed with the recommended application of
the components. In case of other arrangement, heavy malfunction can be the result. Therefore,
the installation instructions on the following pages must be followed strictly.
Caution
Local installation regulations are to preserve safety of electrical equipment. They are not taken
into consideration in this operating manual. However, they have to be followed strictly.
Caution
Bad earth connection may cause electric shock to persons, malfunction of the total system or
damage of the electronic unit! It is vital to ensure that proper earth connection is done.
7.1 Mounting the Electronic Unit
The housing can be mounted in a control cabinet or directly beside the machine. All
connections are led into the housing through glands and are connected to the plug-in screw
terminals according to the wiring diagram (fig. 6)
fig. 4: Wiring path inside the housing E600002e

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Caution
The processor board is mounted to the housing cover. Improper handling may damage the
fragile electronic equipment! Don’t use rough tools such as screwdrivers or pliers! Touch
processor board as little as possible! Touch earthed metal part to discharge static electricity
before open the housing!
fig. 5: Screw terminal arrangement on the electronic unit E600003e

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7.2 Wiring Diagram
fig. 6: Wiring diagram EMGZ621A E621A0011e

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7.3 Mounting the Force Sensors
Mounting of the force sensors is done referring to the FMS Installation manual which is
delivered together with the force sensors. The connection between the force sensors and the
electronic unit is done using 2x2x0.75mm2[AWG 18] shielded twisted pair cable. (With cable
length below 15m, 2x2x0.25 mm2[AWG 23] is also suitable.) The cable must be installed
separate from power lines.
Wiring to the terminals of the electronic unit is done according to the wiring diagram (fig. 6).
If two force sensors are used per measuring point, the cables are wired parallel (ref. to wiring
diagram, channel 1). If wiring is made using 6 wire circuit (ref. to wiring diagram, channel 2)
the solder bridges must be modified (ref. to „8.2 Configuring the electronic unit“).
Force sensor excitation can be made using 5VDC (default) or 10VDC (ref. to
„8.2 Configuring the electronic unit“).
Note
The force sensor signal consists of only a few mV and is therefore susceptible to external
influences to the cable. To increase immunity to interfering use one pair of the twisted pair
cable for +signal and –signal.
Note
Connecting the shield of the signal cable to the electronic unit and to the force sensor may
cause ground circuits which may interfere the measuring signal massively. Malfunction can be
the result. The shield should be connected only to the electronic unit. On the „force sensor
side“, the shield should stay open.

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8Operating
8.1 View of the Operating Panel
fig. 7: Operating panel EMGZ621A E621A007
fig. 8: Main operating menu EMGZ621A E621A005e

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8.2 Configuring the Electronic Unit
Prior to the first calibration, the following settings must be done (ref. to „9. Parametrization“):
System parameters
Language Required display language
Measuring system Metric (default) or US standard
Parameters EMGZ621A
Force of sensor Ref. to nameplate of the force sensor
Unit of sensor Ref. to nameplate of the force sensor
Sensitivity FMS force sensors = 1.8mV/V (default)
Scale output 1...4 Which tension feedback refers to 10V resp. 20mA?
Config. output 0-10V and 0...20mA (default)
or 0-10V and 4...20mA
or -10V...+10V
Notice: With a tension signal 0...10V, tension and current output
are active at the same time.
Jumpers for the analog outputs (ref. also to „14. Technical Reference“)
Channels 1 / 2 / 3 / 4 0...10V (Default) or ±10V,
corresponding to parameter Config. output
Note
Wrong setting of the parameters may cause malfunction of the electronic unit! Setting of the
parameters must be done carefully prior to setting into operation!

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8.3 Calibrating the Measuring Amplifier
The calibration is done for each channel separately. It can be calibrated using the „simulating
method“ or the „mathematical method“:
Simulating Method (recommended)
The following instructions are referring to a
setup and calibration on-site. The material
tension will be simulated by a weight (fig. 9).
Check force sensors
•Connect both force sensors (A and B) (ref.
to wiring diagram, fig. 6).
•Check if both values displayed (A and B)
are positive when loading the sensors in
measuring direction. If not, exchange
terminals +signal and
–signal of the referring channel on the
measuring amplifier.
Find offset
•Insert material or a rope loosely to the
machine.
•Press MODE key. Search and select the module Spec.F EMGZ621A 1 and the special
function Find offset A with the ↑↓↵keys (fig. 8).
•Find offset for channel A by pressing the ↵key for 3 seconds (fig. 8). The electronic unit
calculates automatically the new offset value for channel A. The display will return to the
main operating menu.
•Repeat the procedure written above with special function Find offset B (fig. 8). The
electronic unit calculates automatically the new offset value for channel B. The display will
return to the main operating menu.
(The offset may alternatively be found with the digital inputs Find offset A / Find offset B; ref.
to wiring diagram.)
Find gain
•Load material or rope with a defined weight (fig. 9)
•Press MODE key. Search and select the module Spec.F EMGZ621A 1 and the special
function Calibration A with the ↑↓↵keys (fig. 8).
•Set the force referring to half of the applied weight into the display with the ↑↓keys and
confirm with ↵key (fig. 8). The electronic unit calculates automatically the new gain A
value. The display will return to the main operating menu.
•Repeat the procedure written above with special function Calibration B (fig. 8). The
electronic unit calculates automatically the new gain B value. The display will return to the
main operating menu.
Note
Both bearings of a measuring roller bear each the half of the acting total force. Thus you must
input only the half of the calibrating force during calibration of the gain factor! Otherwise the
resulting material tension (A+B) will be calculated incorrect!
fig. 9: Calibrating the measuring
amplifier C431011e

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Mathematical method
If the material tension cannot be simulated, calibration has to be done by calculation. This way
of calibrating is less accurate because the exact angles are often unknown and the effective
mounting conditions, which usually deviate from the ideal, are not taken into account.
•Offset adjustment is done as written under „Simulating method“.
•The Gain value will be calculated by the following formula and then inputted in the
parameters Gain A / Gain B (refer to „9.5 Description of the parameters EMGZ621A“).
fig. 10: Force vectors in the FMS force measuring bearing C431012e
Definition of symbols:
αangle between vertical and measuring
web axis FBmaterial tension
βangle between vertical and FMF
Groller weight
γwrap angle of material FMmeasuring force resulting from FB
γ1entry angle of material FMeff effective measuring force
γ2exit angle of material
δAngle between measuring web axis and FM
()
22/sinsin 1 ⋅⋅
==
γδ
ckBGainFeedbackAGainFeedba

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8.4 Additional Settings
Setting the low-pass filters
The measuring amplifier provides 1 low-pass filter for the display and 1 low-pass filter for
each output signal. They are used to prevent noise which is added to the signals.
The low-pass filters are configured by setting its cut off frequency to an appropriate value.
The cut off frequency is set in the system parameter Lowpass display or in the parameter
EMGZ621A Lowpass output (ref. to „9. Parametrization“). Signal variations which are faster
than the cut off frequency are then suppressed. The lower the cut off frequency, the more
sluggish the display value resp. the output signal will be.
Note
If the cut off frequency is set to a value too low, the output signal will become sluggish. It may
be that the feedback value is no longer suitable for control loop applications. You have to pay
attention that the cut off frequency is set to a suitable value.
Setting the limit switches
The measuring amplifier provides 3 limit switches which can be tapped at the digital outputs.
The limit switches are actuated when the feedback value exceeds (Max. Limit A+B) resp.
undershoots (Min. Limit A+B) the force values stored in parameters Min. limit A+B resp.
Max. limit A+B. The limit switch „|A–B| > limit“ is actuated if the difference of the 2
measuring values is higher than the force stored in parameter |A–B| > limit.
Tapping of the limit switches is done according to the wiring diagram (fig. 6).
Gain switching
If a measuring point is operated with varying measuring conditions (i.e. different material
paths), the gain value of each channel may be switched between two values depending on the
material path. The additional gain values must be calibrated also during setup, using the
special functions Calib. gain 1A / Calib. gain 1B. The procedure is identical as with
Calibration A / Calibration B (ref. to „8.3 Calibrating the measuring amplifier“).
Switching is done using the digital inputs „Switch Gain A“ / „Switch Gain B“ (ref. to
parameters Gain 1 A / Gain 1 B).
Wiring of the dig. inputs is done according to the wiring diagram (fig. 6).

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9Parametrization
9.1 Schematic Diagram of Parametrization
fig. 11: Parametrization EMGZ621A E621A006e
The parameters are split into the modules system parameters and parameters EMGZ621A 1. The
parameter changing mode is activated by pressing the PARA ↵key for 3 seconds. The required
module is then searched with the ↑↓keys and selected with the PARA ↵key (fig. 11). Each
module has its own parameter set. Generally, the parameters are settable using the keys as
follows:
choose and enter
switch the selections or increase / decrease numeric values,
as well as change the sign
change the decimal (while inputting a numeric value) or abort setting
↵
↑↓
←

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9.2 List of the system parameters
Parameter Unit Min Max Default Selected
Language English, French, Italian, German
Measuring System Metric, US standard Metric
Lowpass display [Hz] 0.1 10.0 1.0
Identifier [-] 0 255 0
Baud rate 2400, 4800, 9600, 19200 9600
9.3 List of the parameters EMGZ621A
Parameter Unit Min Max Default Selected
Offset A [Digit] –8000 8000 0
Gain A [-] 0.100 9.000 1.000
Gain 1 A [-] 0.100 9.000 1.000
Offset B [Digit] –8000 8000 0
Gain B [-] 0.100 9.000 1.000
Gain 1 B [-] 0.100 9.000 1.000
Force of sensor [N, kN, cN] 1 9999 1000
Unit of sensor N, kN, cN N
Sensitivity [mV/V] 0.1 3.0 1.8
Min. limit 1) 2) 0
Max. limit 1) 2) 0
|A–B| > limit 1) 2) -
Lowpass output 1 (A–B) [Hz] 0.1 200.0 10.0
Scale output 1 (A–B) 1) 2) -
Config. output 1 (A–B) 0...20mA, 4...20mA 0...20mA
Lowpass output 2 (A+B) [Hz] 0.1 200.0 10.0
Scale output 2 (A+B) 1) 2) -
Config. output 2 (A+B) 0...20mA, 4...20mA 0...20mA
Lowpass output 3 (A) [Hz] 0.1 200.0 10.0
Scale output 3 (A) 1) 2) -
Config. output 3 (A) 0...20mA, 4...20mA 0...20mA
Lowpass output 4 (B) [Hz] 0.1 200.0 10.0
Scale output 4 (B) 1) 2) -
Config. output 4 (B) 0...20mA, 4...20mA 0...20mA
1) [N, cN, kN] if measuring system = metric
[lb, clb, klb] if measuring system = US standard
2) A force value can be input. The value consists of 4 digits. The
position of the decimal point depends on the parameter
Force of sensor

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9.4 Description of the system parameters
The parameter changing mode is activated by pressing the PARA ↵key for 3 seconds. By
pressing the PARA ↵key again, the system parameters are selected (ref. also to fig. 11).
Language
Use: This parameter stores the display language.
Range: English, French, Italian, German
Measuring system
Use: This parameter indicates the measuring system to be used. If it is set to
metric, all force values are shown as [N, cN, kN]. If it is set to US
standard, all force values are shown as [lb, clb, klb].
Range: Metric, US standard Default: Metric
Lowpass display
Use: The electronic unit provides a lowpass filter to prevent noise which is added
to the integrated display. This parameter stores the cut off frequency. The
lower the cut off frequency, the more sluggish the output signal will be. Due
to this filter, the value shown in the display will be much more stable in the
case of high fluctuations of the force value.
The lowpass display filter is independent to the other filters.
Range: 0.1 to 10.0 Default: 1.0
Increment: 0.1 Unit: [Hz]
Identifier
Use: This parameter stores the ident number of the device when linked to
PROFIBUS, CAN-Bus resp. DeviceNet.
Range: 0 to 255 Default: 0
Increment: 1 Unit: [-]
Baud rate
Use: This parameter stores the speed of the serial interface (RS232). The other
settings are fixed: 8 data bits, even parity, 1 stop bit („8 e 1“).
Range: 2400, 4800, 9600, 19200 Default: 9600
Unit: [Baud]