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.

Using 10K Thermister for 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.

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Measure temperature using ICP/DAS I-7018 Thermocouple Module.

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.

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