Kai, My statement suggesting that Prahlad get a consultant wasn't mean't as an insult - quite the opposite. I have no qualms about getting someone more experienced than I in to assist when I have problems. For Prahlad, this design must work as I gather he is employed or otherwise paid to design this. If it fails there is a cost impact and a reputation also!

The point I'm trying to make is that we've given Prahlad a few suggestions - ground plane is good, ferrite beads etc but to blindly follow the suggestions is probably not too good an idea - the example I gave was that he was willing to sacrifice creepage clearance around the optos for the sake of the ground plane. Obviously the suggestion was applied in the wrong area. Both Kai and myself suggested some work around the optos and SSRs which has been done, so we're moving in the right direction. The other suggestion is to have some clearance from the ground plane to the db9 mounting tags. So maybe we need to explain better when to use a ground plane, ferrite beads and creepage distance etc - what seems obvious to some is not too obvious to others.

Also, in reference to my comments previously regarding the little open-ended tracks on the ground plane - either remove them or move the other tracks so that they can rejoin the ground plane. What is the collective opinion here - if it was a clock line then the distance and width of the track could be critical, but for a general low speed signal line??