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 CI541-DP 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.
The following measuring ranges can be configured PROFIBUSâ DP Bus Module CI541-DP PROFIBUSâ DP Bus Module CI541-DP:
Pt100 | -50 °C…+400 °C | 2-wire configuration, 1 channel used |
Pt1000 | -50 °C…+400 °C | 2-wire configuration, 1 channel used |
Ni1000 | -50 °C…+150 °C | 2-wire configuration, 1 channel used |
The function of the LEDs is described under Diagnosis and displays / Displays PROFIBUSâ DP Bus Module CI541-DP.
The module CI541-DP performs a linearization of the resistance characteristic.
To avoid error messages from unused analog input channels, configure them as “unused”.