Pulse transmitter

The TC-003 digital RTD temperature transmitter is a device designed to transmit the temperature measured by a Pt100 RTD sensor to a PLC digital input. Although it requires only one normal digital 24 VDC input on the PLC, it provides an accurate temperature measurement for use in the PLC program.

It is packaged in a standard ANSI - 2", 50 mm 'hockey-puck' to be installed in the head of a normal industrial temperature probe assembly. The TC-003 transmitter is connected to the normal three-wire PT100 RTD.

It measures the resistance of the PT100 RTD and then calculates the corresponding temperature. It then outputs the measurement as a low speed serial pulse train to a standard PLC digital input.

The PLC receives 16 bits of data in a format ready to load into a 16 bit data register. The PLC register ends up containing the value of the measured temperature in degrees C x 10. The PLC digital input does not need to be a high-speed or counter type input. Any normal 24 VDC digital input is suitable. The rate of data transmission is selected to allow non-time critical operation of the receiving PLC. The shortest pulse time is 100 mS, so the PLC needs to have a maximum scan time of 50 mS.

There is no particular limit to the number of TC-003 transmitters that can be used with a single PLC. It depends only on the number of inputs and program and data memory available.