Well after earthing the frame, taking off the additional Oh Shit!! switch, taking out the driver alarm safety circuit it was still tripping out....so I swapped the Pilz for a standard relay and just wired the E-stops to this....seemed to sort it so I'm presuming that either the Pilz is faulty or my wiring circuit to it was crap....

Now trying to get the driver alarms into the E-stop safety circuit....and failing so far, but it's early days....

Did I say before that I hate electrical stuff.......