ok, so, a LOT of trian and error troubleshooting with re boots and bus connections has reveled that everything is OK until I connect the SL2.
SL2 with probes, SL2 without probes, SL2 via. bus to PC4, SL2 via bus to Archon etc.
Whenever the SL2 is connected the communication with Archon drops.
With 2 PC4's is was fine, add SL2 and communication with anything other than the core Archon 'on board' functions drops.
I tried by old SL1 and everything works fine.
I MUST have a temp probe working or my heaters are useless so thank God the SL1 works.
I am going to buy the iTemp DA probe that connects to Archon via. bus.
Has anyone seen that sort of behavior from an SL2?