Connection of resistance thermometers in 2-wire configuration

When resistance thermometers (Pt100, Pt1000, Ni1000) are used, a constant current must flow through them to build the necessary voltage drop for the evaluation. For this, the module AI523 provides a constant current source which is multiplexed over the 8 analog channels.

Connection example

The following measuring ranges can be configured AI523 - Analog Input Module

Pt100	-50 °C…+70 °C	2-wire configuration, one channel used
Pt100	-50 °C…+400 °C	2-wire configuration, one channel used
Pt1000	-50 °C…+400 °C	2-wire configuration, one channel used
Ni1000	-50 °C…+150 °C	2-wire configuration, one channel used

The function of the LEDs is described under Displays AI523 - Analog Input Module.

The module AI523 performs a linearization of the resistance characteristic.

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