hi,

When we using safety DO module in a SIL3 safety function, there would be two kinds of switching: PP and PM.

I'm quite confused where there are two kinds? what's the benefit of these two? Can they achieve SIL3 with similar wiring?

and, if we choose PM, connect to a relay or a drive, does each M shall have a special wiring? or all the Ms can be mixed and then connect to the same earth terminal?

Thanks so much :)