And the PC is earthed, hence the potential earth loop

sorry my experience on this kit is minimal, what do i need to do to check if this is the problem? Or what can I check

Dont know this system but im assuming the 485 is balanced well with eol resistors to reduce any noise? Also are any of the controllers likely to be on a different phase of the supply to the building? This could also create a potential difference across your 485 net and give you said probs

Faulty controller

I'd be checking earths.

Rare for a controller to die like that without external influence.

Faulty controller

You said that they were dropping off anywhere down the line this doesent sound like a faulty controller but if all is well then good for you!

Id be doing as cubit as these probs can absolutely ruin an installation and make them v unreliable

Edited February 23, 201313 yr by sjsturner

It was a controller, took me 3 days to work it down to it. Bypass the controller by taking the data line out and the network sat healthy, as soon as I added the data line back on controllers started dropping randomly, did several hard resets,took the data line back out and everything loaded back. Network now healthy and working efficiently, defiantly a learning curve with the kantech kit. One thing that did happen is when I went back the job last week my spurs had all tripped, maybe a power issue has caused the controller to fail.

Thanks for the help

Your spurs blow their fuse or did the breaker/ rcd trip the circuit or curcuits?

Lightning strike/s?