compactlogix comm issues

ok fellas here's one that has me dumb-founded. i have 4 1769-L35E's in a panel with 2 panelview plus's. they are all connected through a 16 port managed switch which is how i also poll the plc's for my wonderware. this morning we started having issues with the communications between the wonderware and the plc's. then several of the plc's stopped communicating with the panelviews. i disabled the dasabcip server for all of them and they started communicating with the panelviews again. thats problem one. the second issue and its the real head scratcher. out of the four plc's rslinx only recognizes one of them. the other three are the yellow question mark and red x. they are all the same firmware. i have all the eds files. i am lost as to what the cause could be.

Could be the switch? Is there a spare port available? Since it's managed you should be able to mirror each port in turn and take a look at what sort of traffic is going to each device using Wireshark. This may provide some clue as to what's happening. The switch may also provide some internal diagnostics such as utilization rate for each port.

It's a bit of a long shot but worth a go! Alternatively if you have a spare switch (even an unmanaged one should do) try swapping that out

i have been investigating it and i believe it may be the switch. these sixnet managed switches have given me nothing but issues and on top of that there is a third party guy that is almost 1000 miles away that can remote access this stuff and make changes to it. i had a similar issue on another platform recently and it was the switch. did a little reconfiguring of the network and its cadillacing. but what has me stumped is the fact that some of them werent showing on the panelviews and that deactivating the servers for wonderware fixed that. i am thinking its the switch too. its the only common denominator. i am going to order a 16 port unmanaged switch and try to put it in place and see if that resolves some of the issues. i am thinking that having too many managed switches inline is causing the problem. between the 16 port switch and the wonderware server there are two more managed switches, an unmanaged switch and a prosoft ethernet radio.

Check the number of CIP connections, you're probably hitting the limit of 32. Deactivating your WW connections would free up CIP connections restoring communication.

i havent been able to find how many cip connections these panelview plus's use. i have the wonderware set to use a max of 4 per plc.

You need to check the CompatLogix webpage to see if this is the case. Just type in the ip address into your web browser to see the diagnostics.

CIP connections are eaten up by analog modules in a system. If you many analog cards, and if you haven't checked 'rack optimized' this is were most of them are consumed. If your IO consumes 20-24 connections then adding additional devices like PanelViews, Wonderware, Kepware and MSGs to other PLCs will easily put you over the limit. Double check the diagnostics to make sure this the problem.

If it is, you don't have many options but to limit how many devices can connect to it, or upgrade the PLC.