Real situation: 1. I can measure 12V at ECOM(pin28) when floating. 2. I know EGND for IDO usage. Question : I just have only one external 24V power supply, will it be OK to connect ECOM and EGND together for IDO and Wet contact DI detection at the same time? Answer: Yes. Notice: IDO may have voltage spike on GND when switching an inductive load. This spike may cause DI detection stability problem.