Load Cell & Microvolt Input Modbus or Laurel ASCII Protocol Serial I/O Transmitter

(DIN Rail mounted, digitally programmable. Exceptional accuracy at high update rates.)
  • Selectable Modbus or Laurel ASCII protocol.
  • Digital span adjust from 0 to ±99,999.
  • 20, 50, 100, 250 & 500 mV full scale ranges.
  • Output accuracy: ±0.01% of full scale input.
  • Isolated 10V, 60 mA excitation supply to power up to two 350-ohm load cells in parallel.
  • DIN rail mount package only 22.5 mm thick.
  • Detachable screw-clamp connectors.
  • Optional isolated scalable analog output (4-20 mA or 0-10V).
  • Optional custom curve linearization (Extended main board).
  • Modbus RTU or ASCII modes, 2-wire connection, up to 247 digital addresses.
  • Digital zero adjust from -99,999 to +99,999.
  • Peak value capture and auto-tare.
  • Update rate: to 60/sec.
  • 4- or 6-wire hookup to avoid supply and lead resistance effects
  • Powered by AC or DC
  • Easy setup using Laurel's PC-based Instrument Setup Software.
  • Optional dual solid state relays for alarm or control.
Signal Types & Ranges. Laureate Modbus I/O load cell or microvolt input transmitters are designed for use with load cells, strain gauges and microvolt input signals where exceptional sensitivity and stability are required. A most sensitive full-scale input range ±20 mV can be scaled to ±99,999 counts. The selected input range for the full 0-20 mA output span can be as wide as ±99,999 counts or as narrow as 150 counts, limited only by considerations of electrical noise and time constants of the programmable moving average digital filter.

DIN Rail Mounting. Laureate transmitters are housed in a 35 mm DIN rail case that is only 22.5 mm (0.89") thick. Signal connections are via detachable screw clamp plug connectors.

Modbus Compliance. Laureate Modbus transmitters are fully compliant with Modbus over Serial Line Specification V1.0 (2002). This includes RTU or ASCII modes, 2-wire connection, up to 247 digital addresses, and up to 32 devices per RS-485 line without a repeater. For microvolt DC or load cell signal inputs, output accuracy is ±0.01% of full scale input, as provided by the 16-bit analog-to-digital converter front end. Full conversion accuracy is maintained in the Modbus output. Advanced standard features made possible with Modbus operation include peak capture, auto-tare and latched relay operation, since Reset can be provided via digital commands.

Load cell signal conditioner board for Transmitter, Load Cell & Microvolt InputBuilt-in Load Cell Excitation. An isolated 10 Vdc, 60 mA excitation supply rated can power up to two 350-ohm load cells in parallel. With 4-wire load connection, the transmitter operates in a ratiometric mode to eliminate errors due to supply variations. With 6-wire load connection, it also compensates for variation in resistance of the transducer leads, thereby allowing long cable runs.

Fast Read Rate. All Laureate analog input meters and transmitters use Concurrent Slope (Pat 5,262,780) analog-to-digital conversion, which allows up to 50 or 60 conversions per second, while integrating the signal over a full power line cycle. High read rate is ideal for peak capture and for real-time computer interface and control.

Selectable Signal Filtering . The internal digital readings and analog output can be separately selected to be either unfiltered or filtered.

An unfiltered selection updates after each conversion for fastest response, up to 60/sec, while integrating the input signal over a full power cycle. Fast read rate provides true peak readings and aids in control applications.

A batch average filter selection averages each 16 conversions for an update every 1/4 sec.

An adaptive moving average filter selection provides a choice of 8 time constants from 80 ms to 9.6 s. When a significant change in signal level occurs, the filter adapts by briefly switching to the shortest time to follow the change, then reverts back to its selected time constant. Another choice is Auto, which provides an automatic time constant selection based on the signal noise characteristics.

Easy Setup & Scaling Transmitter programming is via a three-terminal RS-232 port using Laurel's PC-based Instrument Setup Software. This software can be downloaded from this website at no charge. The required transmitter-to-PC interface cable is available from Laurel (P/N CBL03). Laurel's serial output transmitters and meters can also be part of PC-based data logging systems using Laurel's Datalogging Software, which operates under the Laurel ASCII Protocol. A single software command switches between the Modbus and Laurel ASCII Protocols.

Scale and offset can be set by either of two methods:

With the coordinate reading method, the Laureate reads the high and low signal values, and the user enters the desired high an low reading values. The Laureate then calculates the span multiplier and offset. This method is ideal if an external calibration reference is available.

With the manual coordinate method, the user enters the high and low input values in Volts plus the desired high and low reading values. This method is suitable if no external calibration reference is available.

Options include dual solid state relays for local alarm or control and an isolated 4-20 mA or 10V (selectable) analog output, effectively providing a linearized analog transmitter output that tracks the reading that would be transmitted digitally. The analog output provides 12-bit (4096 step) resolution of the output span and is ultra-linear to within one bit. Its accuracy is ±0.05% of span for all signal types, except for AC rms, where accuracy is ±0.1%. Output isolation from signal and power grounds is provided by a separate on-board power supply, which can drive 20 mA into a 500 ohm load for 10V compliance. Output isolation eliminates problems caused by ground loops.

General Specifications- Laureate Serial Output Transmitter, Load Cell or Microvolt Input

Analog Input Range Resolution Input Ohms
DC Voltage 200.00 mV 
2.0000 V 
20.000 V
200.00 V
600.0 V
10 µV
100 µV
1 mV
10 mV
100 mV
1 Gohm
1 Gohm
1 Mohm
1 Mohm
1 Mohm
DC Current 2.0000 mA
20.000 mA,
200.00 mA
5.000 A
0.1 µA
1 µA
10 µA
1 mA
100 ohms
10 ohms
1 ohm
0.01 ohm
Input Resolution 16 bits (65,536 steps)
Input Accuracy ±0.01% of full scale input (determined by ADC).
Output Update Rate, Max 50/sec at 50 Hz, 60/sec at 60 Hz.
Max applied voltage 600 Vac for 20, 200 & 600 V ranges, 125 Vac other ranges.
Over-current protection 25x for 2 mA, 8x for 20 mA, 2.5x for 200 mA, 1x for 5 A.
Serial I/O (standard)
Signal levels RS485 (default) or RS232 (jumper selectable)
Data Rates 300, 600, 1200, 2400, 4800, 9600, 19200 baud
Output Isolation 250V rms working, 2.3 kV rms per 1 min test.
Serial Protocols Modbus RTU, Modbus ASCII, Laurel ASCII (selectable)
Devices on RS-485 Line 32 max without a repeater.
Modbus Addresses 247 max<
Modbus Modes RTU or ASCII, 2-wire.
Modbus Compliance Modbus over Serial Line Specification V1.0 (2002).
Transducer Excitation Output (standard)
Jumper Selection 1 10V @ 60 mA, isolated to 50V from signal ground
Jumper Selection 2 5V @ 50 mA, isolated to 50V from signal ground
Jumper Selection 3 15V @ 60 mA, non-isolated
Dual Relay Output (optional)
Relay Type Two solid state relays, SPST, normally open, Form A
Load rating 120 mA at 130 Vac or 170 Vdc, 28 ohms series resistance.
Analog Output (optional)
Output Levels 0-20 mA, 4-20 mA or  0-10 Vdc (selectable)
Compliance, 4-20 mA