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Application notes
Measure temperature either with the PLC’s built-in analog-to-digital converter, using sensors that output 0–5V or 4–20mA, or with an external temperature module that communicates over a serial port.
Temperature measurement
Thermistors measure temperature in many environments and are rugged and low cost, but non-linear. This note explains how to connect a 10K Precon thermistor to the PLC’s on-board ADC, and how to use a look-up table and interpolation to calculate accurate readings from the non-linear input.
Thermocouples are widely used in industry, but their very low output (microvolts) needs amplification to reach the 0–5V the PLC’s ADC expects. Alternatively an ICP DAS I-7018 module provides 8 built-in thermocouple ports. This note shows how to communicate with I-70xx modules over the RS485 port.
Our engineers can advise on sensor selection, signal conditioning and PID loop tuning.