PLC5 w/BCM Modules - Want to add Ethernet

[JIM60406 0]

We have a pair of old PLC-5's (5/40's) that are backed up using BCM modules. I am considering changing out the processors to 5/40E's to allow Ethernet Communications. We'll leave the BCM intact controlling two of the DH's (RIO & DH+). I'd love to do some sort of migration but time is short so a simple processor upgrade will have to suffice. We'll be attaching this to a DeltaV system via a Mynah VIM so we need Ethernet I/P. 1) Anyone know of any conflicts between an Ethernet Processor (1785 L40E) and a BCM Module? 2) Anyone know of any conflicts between an Ethernet Sidecar (1785 ENET) and a BCM Module? Those Ethernet Processors are sure expensive!

[TimWilborne 108]

I don't mess around with too many PLC5s but don't the 5/40s have an RS-232 port? Are they compatible with the 1761-NET-ENI? Not lightening fast, but should work for a backup

[Ken Roach 194]

PLC-5E and 1785-ENET will both work with the 1785-BCM backup communication modules, and 1785-BEM expansions if you have them. If you do have both BCM and BEM, you'll have to skip one slot after the 1785-ENET because BCM and BEM must be in the same logical Group. If you go with 1785-ENET Sidecar, plan on possibly doing a firmware upgrade to your PLC-5 controllers to support the Sidecar. The new (two years ago, anyhow) 1785-ENET hardware has a 10/100 Mb/s Ethernet RJ45 connector right on the front so that's an advantage over the antique AUI port. Be aware also, of course, that the 1785-BCM won't manage the IP addresses of the controllers. Does Emerson/Mynah assure you that their interface can do PLC-5 style addressing ? I expect that it can, but I have a long history of hearing, um, "overpromises" regarding DeltaV networking capabilities.

[paulengr 44]

Yes, the Ethernet processors are vastly overpriced. The whole idea is to price them significantly higher than a CLX processor to drive you over to the new stuff. I noticed that you said Ethernet/IP though. PLC-5's will support DF-1 over Ethernet/IP and explicit messaging but they will not support anything else such as unsolicited messaging, and without that, you won't be doing producer/consumer I/O. So effectively unless you are doing MSG instructions, don't plan on doing Ethernet I/O with a straight PLC-5 Ethernet conversion. There is a way. You can put a DeviceNet card in the PLC-5 chassis, then put a DeviceNet/Ethernet bridge in (even a headless CLX chassis will work). Or you can try to do it via a Digi One IAP. I've been doing some I/O with the latter and I can honestly say that it works for quite a while but something in there just isn't all that stable and over a period of months, it will eventually lock up on you and have to be rebooted (the Digi One that is). Same result with the competitors though so it's not like the Digi is the only culprit.