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4-Channel Temperature Input Module: MD-THRT4

The MD-THRT4, used with a PT100Ω temperature sensor, can measure temperatures between –100 and 500 ℃ with a precision of ±0.5%.


Item Description
Channels 4
Operating Temperature -10 ~ 50 ℃ ((no condensation)
Operating Humidity 35 ~ 85%RH
Sampling Rate 200ms per channel
Input RTD Sensor (PT100)
Allowable Line Resistance 10Ω or less per line from the module to the temperature sensor
Precision ±0.5%
Conversion Speed 240ms per channel
Communication Method RS-485
Packet Transmission 3ms
Isolation Method No Isolation

MD-THRT4’s Sampling Frequency

The sampling rate of the Temperature Input Module is 200ms per channel, and is constantly sampling the temperature sensor. Reading the temperature returns the most recently sampled value.

The Temperature Input Module samples all channels at once, so at 200ms per channel, the total sampling time for four channels is 800ms. Therefore, there is no benefit in reading at a rate greater than 800ms, as it will always return the same value.

When the system is first powered on, all four channels are scanned once. Reading at this time will return an invalid value. Please allow at least 800ms from the time the system is powered on before reading from the module.

Return Value

The return value is the temperature in °C multiplied by 10. In other words if the module returns the value 205, the actual temperature is 20.5 °C.

If an error occurs, the following values may be returned.

Value Description
20001 ~ 20003 An error occurred while transmitting the value to the CPU
20004 Invalid module ID
20005 Sensor is not connected
55555 Value exceeds valid maximum (500.0 °C)
11111 Value is below valid minimum (-100.0 °C)

Modbus Starting Address

Each module has 4 channels, each with its own unique Modbus address.

Channel 0 1 2 3
Starting Address(base 10) 300 301 302 303
Starting Address(base 16) 12C 12D 12E 12F
Address (base 10) used by HMI (SCADA) 40301 40302 40303 40304

Module ID (Modbus Slave Address) Assignment

On the front of the module, there is a rotary switch labeled ID, that is used to select the Modbus slave address for the module. When installing multiple modules of the same type, the ID for each module should be unique.

Rotary switch position 0 corresponds to Modbus slave address 10. If the ID is changed after the module is powered on, it must be power cycled for the new ID to take effect.


modport/md-thrt4/index.txt · Last modified: 2023/05/31 04:35 by COMFILE Technology