HVAC Applications

You can either use the built-in Analog Digtal Converter to connect to temperature sensors that can output 0-5V or 4-20mA, or using external temperature module that are equipped with communication capability to measure temperature.

Document Name



Temperature Measurement

Thermistors can be used to measure temperature in many different environments. They are both rugged as well as low cost but are non-linear device. This application note explains how to physically connect a 10K Precon thermistor to the PLC using the PLCs on board ADC as well as how to use a look up table and interpolation method to calculate accurate temperature readings from the non-linear thermistor inputs.
Thermocouple are widely used in industry but their very low signal output (micro volts) would require amplification to get 0-5V for the PLC ADC input. Alternatively, you can purchase an IPC-DAS I-7018 module that has 8 built-in thermocouple ports. The following application shows how to communicate with I-70xx module via RS485 port.