Thermocouple & RTD Temperature Modbus or Laurel ASCII Protocol Serial I/O Transmitter

(Exceptional linearity & accuracy at high update rates. DIN Rail mounted, digitally programmable.)
  • Selectable Modbus or Laurel ASCII protocol.
  • Also compliant with Laurel ASCII protocol (selectable).
  • 2, 3 or 4-wire RTD connection with lead resistance compensation.
  • User selectable spans from entire TC or RTD range down to 15.0°
  • Peak value capture.
  • Detachable screw terminal connectors.
  • Optional isolated scalable analog output (4-20 mA or 0-10V).
  • Modbus RTU or ASCII modes, 2-wire connection, up to 247 digital addresses.
  • Input for 100 ohm platinum RTDs with DIN and ANSI curves.
  • Upscale or downscale open sensor indication.
  • Output update rate to 60/sec.
  • DIN rail mount package only 22.5 mm thick.
  • Easy setup using Laurel's PC-based Instrument Setup Software.
  • Optional dual solid state relays for alarm or control.
Signal Types & Ranges. Laureate™ TM Series serial output transmitters with the temperature signal conditioner board provide a linearized, highly accurate, stable and repeatable transmitter output for multiple thermocouple types and 100 Ohm platinum RTDs. The meter accepts the outputs of types J, K, T, E, N, R and S thermocouples, plus 100 ohm platinum RTD’s with DIN alpha of 0.00385 and ANSI alpha of 0.003925. The thermocouple or RTD type, unit of measure (°C or °F), resolution (1° or 0.1°), and range are user selectable.

Cold junction compensation automatically corrects for temperature variations at the thermocouple reference junction at the transmitters. Open sensor indication is standard and may be set up to indicate either upscale or downscale. RTD excitation is provided by the transmitter. RTD connections can be of the 2-, 3- or 4-wire type. For 3- and 4-wire connections, the transmitter automatically compensates for lead resistance of the sensor.

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 InputAll ranges for all temperature sensor types are digitally calibrated at the factory. This eliminates the need for field calibration or drift caused by potentiometers found in non-microcomputer based devices.

All Laureate analog input meters and transmitters allow exceptionally fast read rates. Concurrent Slope (Pat 5,262,780) is a method of analog-to-digital conversion that allows up to 60 conversions per second while integrating the input over a full power cycle. Fast read rates provide true readings and fast response for PID control applications. Peak value capture is standard. Full conversion accuracy is maintained in the Modbus output.

Laureate TM Series transmitters send data as a serial digital signal. RS485 or RS232 signal levels are jumper selectable and can each be associated with either the Modbus protocol or Laurel’s simpler Laurel ASCII protocol.

Modbus protocol operation is fully compliant with the Modbus Over Serial Line Specification V1.0 (2002) for 2-wire, half-duplex connection. This includes RTU or ASCII modes, addressing of up to 32 devices per RS485 line without a repeater, and up to 247 digital addresses. Modbus operation allows devices by different manufacturers to be connected in parallel and be addressed using the same protocol.

Laurel’s Laurel ASCII protocol allows up to 31 Laureate devices to be addressed on the same RS485 data line. It is simpler than the Modbus protocol and is recommended when all devices are Laureates. It also allows use of Laurel’s datalogging software.

Transmitter programming is via the unit's three-terminal serial 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.

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.

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

General Specifications

TC Type Range Conformity Error
J -210°C to +760°C
-347°F to +1400°F
K -244°C to +1372°C
-408°F to +2501°F
T 0°C to +400°C
-257°C to 0°C
+32°F to 752°F
-430°F to +32°F
E -240°C to +1000°C
-400°F to +1830°F
N 245°C to +1300°C
-410°F to +2370°F
R -45°C to +1768°C
-49°F to +3214°F
S -46°C to +1768°C
-51°F to +3213°F
Applicable to all thermocouple types
Calibration NIST Monograph 125 (IPTS-68)
Input resistance 1 Gohm
Input current 100 pA
Max lead resistance 1 Gohm max for rated accuracy
Span tempco ±0.003% of reading/ºC
Reference junction tempco ±0.02 deg/deg
Span tempco ±0.003% of reading/ºC
Overvoltage protection 125 Vac
NMR at 50/60 Hz 80 dB plus selectable digital filter from 80 ms to 9.6 s time constant
CMR, DC-60 Hz 120 dB with 500 W imbalance
CMV, DC-60 Hz 250 Vac from power and earth grounds
Open sensor indication 0 mA or > 20mA output, selectable
Pt 100 RTD Input
RTD Alpha RangeConformity Error
-202°C to +850°C
-331°F to +1562°F
-202°C to +631°C
-331°F to +1168°F
Applicable to all RTD types
Calibration, DIN IEC 751 (IPTS-68)
Calibration ANSI NIST Monograph 126
Configuration 2, 3 or 4-wire connection
Excitation current 0.2 mA
Span tempco ±0.003% of reading/ºC
Zero tempco ±0.03 deg/deg
Sensor lead resistance 2-wire, 10 mdeg/W/deg up to 10 W
tempco per conductor 3 & 4-wire, 10 mdeg/W/deg up to 100 W
Over-voltage protection 125 Vac
Open sensor indication 0 mA or > 20mA output, selectable
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).
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 10V ( 0-500 ohm load )
Compliance, 0-10V 2 mA ( 5 kOhm load )
Output Resolution 12 bits (4,096 steps)
Output Accuracy ±0.05% of output span
Output Isolation 250V rms working, 2.3 kV rms per 1 minute test
Power Input
Standard power 95-240V AC ±10% or 90-300V DC
Low power option 12-30V AC or 10-48V DC
Frequency DC or 47-63 Hz
Power Isolation 250V rms working, 2.3 kV rms per 1 min test.
Case Dimensions 120 x 101 x 22.5 mm.
Case Mounting 35 mm rail per DIN EN 50022.
Electrical Connections Detachable screw terminal connectors.
Operating Temperature 0°C to 70°C.
Storage Temperature. -40°C to 85°C.
Relative Humidity 95% at 40°C, non-condensing.
Specifications Laureate Serial Output Transmitter, Thermocouple or RTD Input
(shown with optional analog output and dual relay output)
Thermocouple Transmitter Connection
RTD Connections with Excitation & Lead Compensation
rtd2nobox Laureate temperature transmitters allow 2-, 3- or 4-wire RTD hookup to the J5 connector. The transmitter applies an excitation current of 0.2 mA, which it monitors to make ratiometric corrections for excitation supply variations.
rtd3nobox In 2-wire hookup, the transmitter senses the voltage drop across the 100 ohm RTD and both lead wires. The effect of the lead wires can be measured and subtracted by shorting out the RTD during transmitter setup.
rtd4nobox In 3- and 4-wire hookup, the transmitter senses the voltage drop across the 100 ohm RTD and both lead wires as well as the voltage drop across the RTD and one lead wire. This allows the transmitter to determine the effect of one lead wire and mathematically subtract the effect of both lead wires.
Operation as a Fast ON/OFF Controller or Supervisory Monitor

tcdraw2With the optional dual solid state relay output option, which has a typical response time of only 17 ms, Laureate temperature meters and transmitters can serve as extremely fast and accurate ON/OFF controllers for closed-loop temperature control. They can also serve as supervisory process monitors and provide alarms or shutoffs when processes exceed normal limits.

Multiple setpoint operating modes are individually selectable for each relay, as explained in the dual-setpoint controller page. Relay duty cycles and chatter can be minimized with programmable hysteresis and time delays. A band deviation operating mode can be selected for each relay, where an alarm is generated whenever the reading is a selected number of counts above or below the setpoint. With Modbus, relay operation can be non-latching or latching, with reset provided by digital commands.

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