Connection of resistance thermometers in 2-wire \ configuration

When resistance thermometers (Pt100, Pt1000, Ni1000, Cu50) are used, a constant current must flow through them to build the necessary voltage drop for the evaluation. For this, the module AI531 provides a constant current source which is multiplexed over the 4 analog channels.

Connection example

The following measuring ranges can be configured AI531 - Analog Input Module AI531 - Analog Input Module:

Pt100	-50 °C … +70 °C / +400 °C; -200 °C … +850 °C	1 channel used
Pt1000	-50 °C … +400 °C	1 channel used
Ni1000	-50 °C … +150 °C	1 channel used
Cu50	-50 °C … +200 °C (1.426); -200 °C … +200 °C (1.428)	1 channel used

For a description of the function of the LEDs, please refer to Diagnosis and displays / displays AI531 - Analog Input Module.

The module linearizes the resistance thermometer characteristics.

In order to avoid error messages from unused analog input channels, it is useful to configure them as “unused”.