SLC RS500 Comms issues

[Conor 4]

Hi, One part of my plant has this comm's configuration; PLC5 (A=Main PLC) to Scada PLC5 (B=Peripheral PLC) to Scada SLC (C=Peripheral PLC 2) to Scada Each of these PLC's are connected to an unmanaged Hub (16 port) The Scada talks to each PLC I am getting comm's lost on my SLC. It is happening frequently, but with no seeming pattern. It could last a day, or a week or 2 weeks. When I loose comm's I have to power down the SLC to re-establish. Looking in RSLinx when the comm's are lost there is an X through the SLC. Is there somewhere that I can check in the PLC to see where the fault is occuring or maybe is there a cable issue. If this was a cable problem, would this not be happening constantly

[ssommers 20]

What's the SLC model #?

[Conor 4]

It's an SLC 5/05 My problem is that being an SLC I have to power down to reset when I can't get on via the Ethernet port. Does this clear the last error in the processor memory?? Any help with this would be great, as I am really struggling Thanks again Edited 28 Aug 2008 by Conor

[Conor 4]

Ok. We changed out the Hub with a different one and this has worked for the last 16 hrs. What would be the next step if this Hub starts crapping out??

[OkiePC 14]

Have a look at the SLC5/05 comms servicing selection bits. Also, make sure you have a channel diagnostic file established. You can set a bit to determine whether to have the CPU process one message per housekeeping session or process all pending comms each housekeeping cycle. The SLC is not nearly as adept with communications as a PLC5. They are always more sensitive to traffic. A cable problem can be intermittent too, and hard to find using ethernet. I don't have easy access to manuals from home but I hope this helps. Paul

[Conor 4]

Thanks again Paul. I will have to look into the channel diagnostic file, I am not sure if this is set-up. On the housekeeping, do I use a System bit to do this?? I have seen that SLC's don't handle comm's as good as PLC5. I have another SLC, actually the one that I am doing the analogue checking on (in another post). Anyway, when I communicate to it over our network, ControlNet/Fibre/Ethernet it craps out alot, especially if I am trying to do on-line edits. The easiest thing for me is to go over to the SLC and connect directly into a hub that it is connected to. I don't get any of the crapping out then. Thanks again