On a PCD2.M4560 or PCD3.M5560, why the measured PT100 temperature values are not correct if the PT100 sensors are connected to PCD2.W220Z18 or PCD3.W220Z18 modules?

FAQ #102052

On the ‘old’ PCD’s like PCD2.M170 or PCD3.M5540 the PCD internal power supply V+ was at 24V

On the ‘new’ ‘Power-PCD’s’ and the PCD2.C1000 and PCD2.C2000 the V+ is 16,5V

The electrical design of the PCD2/3.W220Z18 was done in that the way, that the internal power V+ of 24V was required to handle all 8 PT100 channels.

Since the ‘Power PCD’s’ and the PCD2.C1000/C2000 have a V+ of 16,5V the driver on the PCD2/3.W220Z18 don’t have enough power to handle all 8 PT100 signals correctly.

To solve the issue, use and connect only up to 7 PT100 sensors to the PCD2/3.W220Z18 or do use a PCD2/3.W350 module, if all 8 PT100 are needed.