ABB AC500 PLC Hardware Manual page 885

Fig. 175: Connection of configurable digital inputs/outputs to the module CI521-MODTCP
The meaning of the LEDs is described in Displays
on page 907.
Connection of Resistance Thermometers in 2-wire Configuration to the Analog Inputs
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 CI521-
MODTCP provides a constant current source which is multiplexed over the max. 4 analog input
channels.
The following figure shows the connection of resistance thermometers in 2-wire configuration to
the analog input AI0. Proceed with the analog inputs AI1 to AI3 in the same way.
2019/04/17
Ä Chapter 1.7.4.1.8.2 "State LEDs"
3ADR010121, 13, en_US
Communication Interface Modules (S500) > Modbus
Device Specifications
885