Deeter Electronics LVCSi User manual

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 1 of 32

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 2 of 32
Table of Contents
1. Introduction ........................................................................................................................3
2. Main Features .....................................................................................................................4
2.1 Sensor Inputs....................................................................................................................................4
2.2 Display ...............................................................................................................................................5
2.3 Analogue Outputs ............................................................................................................................6
2.4 Digital Outputs..................................................................................................................................7
2.5 Serial Communications ...................................................................................................................7
3. Installation ..........................................................................................................................8
3.1 Mounting the Sensor Stem .............................................................................................................8
3.2 External Wiring .................................................................................................................................8
3.2.1 Power Supply ....................................................................................................................................8
3.2.2 Analogue Outputs ............................................................................................................................9
3.2.3 Digital Outputs..................................................................................................................................9
3.2.4 RS485 Communications ................................................................................................................10
3.3 Inverting the LVCSi .........................................................................................................................10
4. Configuration Setup .........................................................................................................11
4.1 Option Menus.................................................................................................................................11
4.2 Level Display ...................................................................................................................................13
4.3 Temperature Display .....................................................................................................................14
4.4 Display Brightness .........................................................................................................................14
4.5 Analogue Output 1.........................................................................................................................15
4.6 Analogue Output 2.........................................................................................................................16
4.7 Analogue Output Calibration........................................................................................................17
4.8 Temperature Sensor Calibration .................................................................................................19
4.9 Digital Output Setup ......................................................................................................................19
4.10 Digital Output Test .........................................................................................................................20
4.11 Communications Setup.................................................................................................................20
5. Operating States ...............................................................................................................21
5.1 Start-up............................................................................................................................................21
5.2 Normal Operation..........................................................................................................................21
5.3 Missing Level Sensor .....................................................................................................................22
5.4 Missing Temperature Sensor .......................................................................................................22
5.5 Current-Loop Fault.........................................................................................................................22
5.6 Supply Voltage ................................................................................................................................22
6. RS485 Serial Communications .........................................................................................23
6.1 Deeter ASCII Protocol ....................................................................................................................23
6.2 Modbus RTU ...................................................................................................................................27
6.2.1 Supported Function Codes...........................................................................................................27
6.2.2 Register Assignments....................................................................................................................27
6.2.3 Bit Assignments .............................................................................................................................28
6.2.4 Broadcast and Exception Responses..........................................................................................30
6.3 Modbus ASCII..................................................................................................................................31
7. Specifications ....................................................................................................................32

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 3 of 32
1. Introduction
The LVCSi is an analogue vertical level sensor with an integrated display meter and output driver
specifically designed for continuous, in-situ monitoring of your tank. It is an extension of Deeter
Electronics’ range of LVCS analogue level sensors and includes a temperature sensing option.
The LVCSi features:
 A display for direct read-out of level and temperature
 Two pairs of analogue outputs (4-20mA and 0-10V)
 Two set point digital outputs
 An RS485 communications port
 IP Rating of IP68
 Stem Lengths up to 2000mm
 Optional Temperature Sensor
 Optional Modbus
Setup menus enable the selection of a wide range of options to suit the installation, with options
saved to non-volatile memory.
The level display range is user-programmable with a choice of length and volume units.
Temperatures are shown in degrees Celsius, degrees Fahrenheit or Kelvin to one decimal place.
The two analogue outputs each have 4-20mA current-loop and voltage output terminals. The
voltage outputs have user-selectable ranges of 0-10V, 0-5V and 0-2V. Analogue Output 1 is
reserved as a level output and Analogue Output 2 can be assigned to level or temperature.
The two digital transistor outputs have programmable ON and OFF set-points and each can be
assigned to activate at level or temperature thresholds.
The LVCSi has an RS485 communications port with a selection of four baud rates and three
communications protocols: Modbus RTU, Modbus ASCII and ‘Deeter ASCII’. The Deeter ASCII
protocol comes as standard and enables remote monitoring of level, temperature and
instrument status. The Modbus protocols are an optional extra and provide for full remote
monitoring and control, including selection of setup options.

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 4 of 32
2. Main Features
2.1 Sensor Inputs
The LVCS range of continuous vertical level sensors feature a magnetic float moving along a stem
to provide a continuous analogue output that indicates liquid level. The output signal is in fact
stepped, with resolutions from 3mm to 15mm depending on the sensor element spacing. Sensor
elements are either reed switches or Hall-effect ICs, the choice depending on customer
requirements such as length, resolution, and operating temperature. Level sensor stems can be
made from a range of materials, the most common being stainless steel, and come in a range of
standard and custom lengths.
Figure 1 – Sensor Thermal Response
A temperature sensor can be integrated into the end of a stainless steel LVCS. The thermal mass
of the steel will dampen the response to rapid temperature changes, as shown in Figure 1 – a
typical response for an LVCSi at ambient temperature plunged into water at 90°C, compared
with a steel reference thermometer probe, 3.2mm in diameter.
Measurement error at thermal equilibrium is less than ±1°C over the full input range of –40°C to
+120°C. (Note that LVCS stems are only specified down to –20°C and Hall-effect versions are
limited to a maximum of +80°C.)

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 5 of 32
2.2 Display
The display is a 2-line by 8-character backlit LCD. In normal operation the top line shows level
information and the bottom line shows temperature. If a temperature sensor is not fitted, the
bottom line remains blank.
The displayed numbers (LOW and HIGH) that coincide with the lowest input level and highest
input level are user-programmable. There is also a choice of decimal-point position, which is
fixed across the LOW to HIGH range, giving maximum display ranges of:
–1.000 to +1.000
–10.00 to +10.00
–100.0 to +100.0
–1000 to +1000
–10000 to +10000
LOW and HIGH display settings can be any number within a range, except the last digit in the
range –10000 to +10000 is always zero. Between the LOW and HIGH settings the relationship
between input and output is assumed to be linear.
The highest input level is at the end of the stem nearest the head. If the sensor is inverted (e.g.
mounted from the bottom of a tank) the LOW number may be set greater than the HIGH
number in order to invert the display.
Units can be appended to the level number. Choices are shown in Table 1.
Table 1
OPTION UNIT COMMENT OPTION UNIT COMMENT
<none> blank
ft Feet
% Percent
‘ Feet
m Metre
L Litre
m Metre Space after number L Litre Space after number
cm Centimetre
cl Centilitre
mm Millimetre
ml Millilitre
in Inch
pt Pint
“ Inch
Gal Gallon Capital G to avoid
confusion with 9
(Note that the 3-character unit ‘Gal’ will be shortened to ‘Gl’ if the number requires 6 characters,
i.e. it has four digits, a decimal place and includes the negative sign.)
Temperatures are displayed in degrees Celsius, degrees Fahrenheit or Kelvin to one decimal
place.
The display backlight is at full brightness for 20 seconds after power-up, 20 seconds after any
button-press, or continuously during any fault condition. The quiescent backlight brightness is
user-programmable between zero and 80%.

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 6 of 32
2.3 Analogue Outputs
Analogue Output 1 is assigned to the level input only. If a temperature sensor is fitted, Analogue
Output 2 can be assigned to level or temperature.
Each output has four ranges: 4-20mA, 0-10V, 0-5V and 0-2V. (If a temperature sensor is not fitted
Analogue Output 2 is limited to the three voltage options.)
The 4-20mA and 0-10V options provide the same output levels, but choosing 4-20mA enables a
fault state to be triggered if the resistance of the current loop circuit exceeds the capabilities of
the driver IC. An open current-loop circuit will cause this fault state to occur. There are also
calibration adjustments for each of the four outputs and the one implemented for a particular
channel is determined by the choice of current-loop or voltage.
Level outputs can be inverted to provide 20-4mA, 10-0V, 5-0V and 2-0V. This is useful for level
sensors mounted from the bottom of a tank.
The full input range of the temperature sensor covers 160 degrees Celsius, from –40°C to +120°C.
The analogue output has four user-selectable input ranges of 160, 100, 80 and 50 degrees
Celsius and the reduced input ranges can be set anywhere within the sensor limits of –40°C to
+120°C. For example, the 100 degree output range could be set to cover the sensor input range –
20°C to +80°C.
Table 2 lists the current-loop and voltage output resolutions for the four input ranges
Table 2
INPUT
RANGE
ANALOGUE
OUTPUT
OUTPUT
RESOLUTION
(Celsius)
OUTPUT
RESOLUTION
(Fahrenheit)
160°C 4-20mA, 0-10
V
10°C/mA, 16°C/
V
18°F/mA, 28.8°F/
V
160°C 0-5
V
32°C/
V
57.6°F/V
160°C 0-2
V
80°C/
V
144°F/V
100°C 4-20mA, 0-10
V
6.25°C/mA, 10°C/
V
11.25°F/mA, 18°F/
V
100°C 0-5
V
20°C/
V
36°F/
V
100°C 0-2
V
50°C/
V
90°F/
V
80°C 4-20mA, 0-10
V
5°C/mA, 8°C/
V
9°F/mA, 14.4°F/
V
80°C 0-5
V
16°C/
V
28.8°F/V
80°C 0-2
V
40°C/
V
72°F/
V
50°C 4-20mA, 0-10
V
3.125°C/mA, 5°C/
V
5.625°F/mA, 9°F/
V
50°C 0-5
V
10°C/
V
18°F/
V
50°C 0-2
V
25°C/
V
45°F/
V

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 7 of 32
2.4 Digital Outputs
There are two open-collector NPN transistor outputs. When inactive (OFF) they require an
external pull-up (maximum of 36V) and when active (ON) they connect to the 0V rail and can sink
up to 50mA.
Each transistor has user-selectable ON and OFF thresholds that can be assigned to level or
temperature inputs. When assigned to level, thresholds are represented as a percentage
between 0% (float at bottom of stem) and 100% (float at top of stem). When assigned to
temperature, thresholds are in degrees Celsius or Fahrenheit.
If the ON threshold is greater than the OFF threshold, the transistor will be active when the input
is high and inactive when the input is low. If ON is less than OFF, the transistor will be active
when the input is low and inactive when the input is high. Between ON and OFF thresholds the
active/inactive state depends on the last threshold the input has passed.
Setting ON equal to OFF is not recommended because some hysteresis is usually required to
prevent the output ‘chattering’ when the input hovers around the threshold. If settings are made
equal, the transistor will be active when the input is above the threshold and inactive below the
threshold.
2.5 Serial Communications
Serial communications are asynchronous using half-duplex RS485 signals with a fixed data
format of 8 data bits, no parity and 1 stop bit. There are four user-selectable baud rates: 2400,
9600, 19200 and 38400.
The LVCSi is a slave device, responding to commands initiated by a bus master.
A simplified ASCII protocol, ‘Deeter ASCII’, comes as standard. This uses ASCII characters in the
displayable range 20h to 7Eh, making commands easy to generate and responses easy to view
and interpret on a PC with readily available terminal-emulation software. Commands are limited
to monitoring of inputs and status information.
The optional Modbus protocols allow for full remote monitoring and setup. The LVCSi conforms
to the Modbus RTU and Modbus ASCII command and response framing standards as a slave
device – see section 6 for details.

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 8 of 32
3. Installation
3.1 Mounting the Sensor Stem
To mount the LVCSi in a tank, first separate the two assemblies:
 unscrew and remove the glass cover of the head assembly
 pull off the LCD surround
 remove the two screws securing the circuit assembly to the support pillars
 slide the PCB assembly forward over the two support pillars
 disconnect the cables from the sensor stem at connectors J1 and J2
Unscrew the stem from the head and mount the stem inside the tank. LVCS stems have a variety
of mounting options to suit customer requirements.
Refit the temperature sensor connector to the 2-way header, J1.
Refit the level sensor connector to J2. J2 can be a 2-way, 3-way or 5-way header depending on the
type of level sensor. 5-way headers are split into a 2-way plus 3-way.
The head is secured to the stem by screwing the two back together.
3.2 External Wiring
All external connections go to the two rows of screw terminals on the underside of the bottom
PCB. Cables must be fed through the ports at the back of the enclosure with enough slack to
reach the screw terminals while the circuit is pulled forward to gain access to these terminals.
The following sections describe connections to the screw terminals. After connections have been
made, reassemble the circuit by reversing the actions and reversing the order of the disassembly
listing in section 3.1.
3.2.1 Power Supply
Power requirements are 15Vdc to 30Vdc at 100mA.
Connect the positive wire to the ‘POWER Vin’ terminal and the negative wire to ‘POWER 0V’.

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 9 of 32
3.2.2 Analogue Outputs
There are two independently driven analogue outputs, each having terminals for voltage and
current, making four analogue outputs in total. These are arranged as a single block of 8 screw
terminals on the underside of the bottom PCB. (If a temperature sensor is not fitted, this is a 6-
way connector with no provision for the Analogue Output 2 current-loop).
Analogue Output 1 is always assigned to level. Output 2 can be assigned to level or temperature.
Connections can be made to both sets of terminals from a single analogue output and the
voltages and currents will correlate. However, if 5V or 2V output ranges are selected the current
will be limited to ranges of 4-12mA or 4-7.2mA. Also, the calibration adjustments used for a
channel are based on the choice of current or voltage output (see section 4.7), so the other
output will be slightly out of adjustment.
3.2.3 Digital Outputs
Terminals DO1 and DO2 are open-collect transistor outputs and an external pull-up is required
in the off state.
Space limitations mean that separate 0V or power supply terminals are not available for the full
range of equipment that could be connected to the digital outputs. Depending on the nature of
the equipment, wires may share with the POWER 0V or Vin terminals as shown in the examples
of Figure 2.
Figure 2
The transistors outputs are protected from transient voltages, but for inductive loads, further
suppression is recommended close to the source. In the case of a relay, a diode (e.g. 1N4001) will
provide protection, as show in Figure 2.

LVCSi Continuous Vertical Level Sensor with Integrated Display
Page 10 of 32
3.2.4 RS485 Communications
The RS485 serial communications port is half-duplex, using the balanced-pair lines D+ and D–.
Connections to the bus master are:
LVCSi MASTER
D+ D+ or A
D– D– or B
0V 0V or SC or G
A line-termination resistor can be enabled by moving LK1 to the TERM position. For a multi-drop
configuration only the end device should have this link in the TERM position.
3.3 Inverting the LVCSi
The LVCSi can be mounted to the top or bottom of a tank. Default settings are for top-mounting,
with low analogue and display levels associated with the float at the end of the stem away from
the head.
If mounting the LVCSi the other way up (e.g. below a tank):
 Mount the display the other way up inside its housing
 Reverse display settings by making the ‘LOW’ level greater than the ‘HIGH’ level (see
section 4.2)
 Select ‘INVERT’ for analogue outputs (see section 4.5)
 Convert digital output threshold percentages by subtracting from 100%