SLC 5/03 Burnt port

OK seen this one.
5/03, I have burnt (charred) two processors I am hooked to a PV600 on DH485 on the RJ11 port. Replaced P/S Back Plane and processor at different times, I am thinking one infected another and now am waiting on New components, to replace them all, has anyone seen this, I HAVE NEVER IN MY 20+ YEARS

When the devices are NOT connected, do you measure any significant AC or DC voltage between the device grounds or commons?

How far apart are the two devices? Are you connect through AIC module(s)?

this might not be even remotely connected with your problem so don't let it send you on a wild goose chase ...

but ...

you need to be aware that two of the contacts in your processor's DH-485 port are used to supply 24VDC and a DC return to "other" devices which might be connected there ...

in other words, there's HOT STUFF and a RETURN PATH in that plug ... I've heard horror stories of bad things happening when the cable hooked into that port wasn't treated with respect ...

What's the history ? Were these systems just working and then went Pfft, or are they being hooked up for the first time ?

The only cable that should be used to connect a DH485-equipped PanelView Standard terminal to an SLC-5/03 Channel 1 DH485 port is a 1747-C10 or -C20.

These cables have a flat "AMP" connector on the PanelView side, and a RJ45 connector on the SLC-5/0x side.



The RJ45 style plug on the PanelView itself is for connecting a 1747-PIC or 1747-UIC. It doesn't have the hot 24V pin.

That hot pin on the SLC-5/0x DH485 port has burt more than one Ethernet port up in the past when folks just assumed that any two devices with RJ45 connectors could be connected together.