LCA20 Load Cell Amplifier with Data and Relay outputs

LCA20 Load Cell Amplifier with Data and Relay outputs

  • Measurement speeds of 10 / 80 samples per sec
  • 5 V excitation supports up to 10 x 350 R load cells
  • Sensitivity from 0.5 to 7.8 mV/V
  • Full digital set–up using PC or keypad
  • 3 x configurable digital inputs e.g. for auto tare, peak hold and reset
  • Fully isolated 4-20 mA and 0-10 V analogue outputs

This very flexible digital load cell amplifier for weighing single or multiple load cell applications, offers an easy one-pass calibration and fast setup.  It is also equipped with relays, data port and display.

The LCA20 load cell weight indicator offers options of local or remote LCD displays, isolated 4-20 mA 0-10 V analogue outputs, relay outputs for control or alarm functions, for example, in crane overhead alarms, and also for, in-flight compensation commonly used in silo bag filling applications. The RS232 or RS485 options provide for digital communications (including setup) and can support label or ticket printers.

Analogue and digital output, set point and display capabilities AC or DC powered, IP65 NEMA 4 protected.

IP65 bulkhead mounting ABS case - also available as a DIN rail or PCB module - model LCB-20

View LCA20 Video on YouTube to learn more.

Can be used in conjunction with our LCI load cell failure alarm, which is designed to continuously monitor the condition of individual load cells and activate an alarm when faults in the system are detected, therefore providing increased safety and cost savings onsite for all weighing systems.

The input is of the Load Cell/Strain Gauge type. With transducer excitation voltage of 5 volts @ 160mA to drive 10 x 350R bridges
Compensation by ± sense wires for cable and safety barrier losses down to 3V excitation
Load cell sensitivity range 0.5 to 7.8mV/V (2 ranges configured from keypad or communications port)
Initial offset is no greater than ± 0.15mV (15uV/V) which is cancelled during auto calibration
Speed 10 and 80 Samples Per Second (configured from keypad or communications port)
Factory mV/V calibration accuracy ± 0.05% FSD being typical
Drift ± 2 ppm per degree C @ 2.5 mV/V typical
Non Linearity before linearization 10 pt typical
Internal Resolution 20 bit or 1 part in 1,000,000
Noise Free Resolution @ 10 Hz 17.5 bit or 1 part in 180,000
Contact inputs are available for auto tare, print and peak hold reset and are volt free
Analogue Outputs
Drive 4-20 mA up to 1 Kohm and 0-10 volts up to 2 mA
Accuracy ± 0.15% of range, typical
Resolution as for display up to 13 bits / 4.5 digits. Settling time 350 mS to within 1% of step change
Isolation ±130 V RMS or DC max to analogue input or any other port
Power Supplies
LS1 110 V-120 V AC or 220 / 230 V AC 50-60 Hz 10 W
LS3 9-32 V DC 10 W isolated
Data Retention/Protection
Retention 20 years for set up values, minimum of 100,000 write cycles
Protection of data and function(s) Watchdog timer giving repeat auto resets. Impending power detection and hold off. Calibration and Toolkit lock feature
Other Options & Accessories
2 Set Points Output through 5 A 240 V AC SPCO Relays, with a latching option
Communications Port For data transfer or print via :-
RS485 Enabling up to 253 units to be multi dropped
RS232 For 1 to 1 connection and standard printer drive and large displays
Printer Operation By closure of volt free contact or continuous ASCII stream
Baud Rates 2400, 4800, 9600, 19200, 38400, 57600, 76800, 115200
Die Cast Case Sealed to IP65 / NEMA 4 with external dimensions of 220 x 120 x 80mm max
Stainless Steel Case Sealed to IP65 / NEMA 4 with external dimensions of 224 x 160 x 90mm
PCB Only (Eurocard) (LCB20) 100 x 160 X 57mm for rack or customers enclosure
Storage Temperature -20 to +70ºC
Operating Temperature -10 to 50ºC
Relative Humidity 95% maximum non condensing
CE Environmental Approvals European EMC Directive 2004/108/EC, Low Voltage Directive 2006/95/EC
LCA Dimensions



  • LC Toolkit : Version 1.8.0 The LC Toolkit software for Windows will allow a connection with the LCA20 via an optional on-board communications module LC4 or via an optional programming cable PGM1.
Q: What Protocols are available with the LCA20?

A: There are 4 Protocols
CP=128 = Mantrabus 1 a hex based protocol. Most popular, easiest to deal with from programming point of view.
CP=131 = Mantrabus 2 updated version of Mantrabus1
CP=133 = Mantra ASCII 2 based protocol designed for old teletype machines, looks easier but actually more complicated to programme.
CP = 132 Modbus RTU used a lot in PLCs. 3rd Party S/W available. Hex based.
Or alternatively set CP=127 and the device will transmit an ASCII string every display update (used for continuous printout to either printer or display.

Q: Does stainless steel case for LCA20 have stainless steel glands?

A: No plastic PG9 glands.

Q: Does the 4-20 mA output on an LCA20 have galvanic separation?

A: No but it does have electrical isolation up to ±130V RMS 

Q: How do you view the live reading on the LCA20 without Auto Tare and having to calibrate again?

Go to the 'measurement' section in the LCA Toolkit.
Note the reading in the 'Tare' value box and then change the value to zero. Click on the 'Tare' button and the unit will display live reading.

Alternatively, using the keypad:
Go into the menu and pick AT Mnemonic.
Note the reading down and then set to zero.
Press return and then the unit will display live reading.
To reset Auto Tare re enter value in AT Mnemonic screen which you noted down.

Q: What is the maximum length of cable we could connect between a LCA20 unit and a load cell unit?

A: It would depend on many different factors:
The quality of the cable
The type of cable
Whether it was 4 or 6 core
The number of load cells
With the best quality of cable in an ideal environment and with little or no interference we have had operating at 200 metres.

Q: LCA20 / SMW can they handle tension and compression?

A: Yes

Q: Is it possible to connect two LCA20s to one load cell?

How would the scaling of each remain stable in the event of a failure of one or the other ?
Can the output of the load cell be connected to both LCAs? With perhaps a resistor network holding the input of the second to a reference ?

A: This is done using 6 wire, with the second LCA20 as 5 wire (no "+" excitation).
You could have two 6 wire with two blocking diodes (for redundancy).
Or a separate power supply and two 5 wires. 

Q: How do I factory reset a ADP / ADW / LCA20 / SMW?

A: Hold down the Scroll and reset key and then power cycle the unit.

Q: Can I use a laptop to set up the LCA20?

A: Yes, by means of the optional PGM1 Programming Cable and the LCA Toolkit. The option to use the LCA20 keypad is also available.

Tech. Tip: Hover and Click on any of the icons below.
LCA20 Base unit supplied in an IP65 Rated NEMA4 ABS Case
LCA20 Base Unit
LS1 AC Power Supply- Selected by wiring configuration during installation, the LS1 allows the unit to be powered from either 110 or 230VAC mains voltages at either 50Hz or 60Hz.
Maximum power requirement is 10W. Installation must be carried out by a competent person who must ensure that the mains supply to the unit is fitted with a fuse or other current operated protection device rated at 100mA for 110V operation or 50mA for 230V operation.
LS3 DC Power Supply-The LS3 accepts DC voltages from 9 to 32VDC. The DC source must be able to supply a start-up current of 3A for 20mS. The power requirements once started is a maximum of 10W.
Power Supply Option-None Selected
AC Power Supply 110/120V, or 220/230V AC
DC Power Supply 9-32V DC
There are two types of programming modules available. Both have 4 keys for menu navigation and a 4½ digit LCD display.
The LP1 is an On-board programmer which is permanently fitted to the LCA20.
The LP2 is a hand held programmer that can be used to setup and calibrate the LCA20 and then removed leaving a blind amplifier/controller.
Both fit into the FCC68 6 way connector marked on the PCB as J8.
Display Option-None Selected
On-Board Programmer
Remote Handheld Programmer
Relay Output Option-The Relays provide for 5 amp switching at 240VAC.
The optional Relay output module, RL1, provides two output control signals which can be used for switching functions such as ON/OFF control and alarm indications. The relays are activated by the values programmed for the Set Points.
Relay Output Option-None Selected
Relay Output Module 2 Set Points (2 x SPCO 5A 240V AC )
The optional LC4 communications module acts as a two-way data link for the LCA20 providing an electrically isolated multi-standard interface.
The LCA Toolkit software for Windows will allow a connection with the LCA20 via an optional on-board communications module LC4 or via an optional programming cable PGM1.
Communication Option-None Selected
RS485/232 Communications (supports MODBUS RTU, ASCII, MANTRABUS 1 & MANTRABUS 2)
JBA Junction Box Active in Enclosure
JPA Junction Box Active (PCB)
The Strain Gauge Junction Box is used to sum the outputs from up to 4 Strain Gauges to allow them to be connected to the LCA15 Strain Gauge Indicator/Controller.
JBA Option-None Selected
JBA Junction Box Active in Enclosure
JPA Junction Box Active OEM PCB Board Only
Junction Box PCB Board Passive
Programming Cable PGM1 For communicating with the module using the LCA Toolkit for configuration or firmware updates you have the option of using the PGM1 programming cable. This is a cheaper option than fitting an LC4 communications module and is intended for engineers to use in the field for configuration or for in-house configuration of modules that are to be installed with no communications module.
D2 DIN Rail This DIN rail mounting option accepts a LCB20 board assembly for Top Hat type DIN rails. If these parts are purchased separately then the copper parts of the LCB20 board fingers require cutting off.
LTL Transparent Lid The LTL is a clear perspex lid which is fitted to the LAC. It is mainly used when the On-board programmer (LP1) is fitted to the LCB20 PCB.
Programming Lead
DIN Rail Mounting Fixture
Transparent Plastic Case Lid
  • LCA20 Base Unit
  • Power Supply Option-None Selected
  • Dispay Option-None Selected
  • Relay Output Option-None Selected
  • Communication Option-None Selected
  • JBA Option-None Selected