AB SLC50/5 Communications Problem

I am having some issues with my slc 500's keeping their ip addresses. I thought you guys might be able to confirm some of my thoughts. Anyways let me bounce this off you and see what you think.

I have a lab with 6 SLC 50/5's, and 16 computers. All the computers return directly to a switch. The 6 plcs connect to a N-Tron hub and a single line back to that same switch. All computers in the lab reset every night at 12:00am. We are running windows 7 and have the latest version of Rockwell software. For some reason my PLC's are losing their Mac address to ip address relations. I use bootp to make the relations and for each one I enable the bootp, all says successful. I can see all the mac addresses and their ip relations in bootp. When I use Rslinx classic I install the Ethernet/ip driver and use a browse remote subnet as I have done for years. I can now only see 3 of the 6 plc's. even though bootp can see them all??? Its like the plc's can't retain their ip addresses relations. SLC 500's should be able to retain their ip addresses right? It should be a only one time setup. the batteries are all good in the cpu's. Did a load test on them and they are all around what they should be. no batt light showing on the cpu's. Any thoughts on the matter? I can't think of anything else I can try. the only thing that I think is strange is that on the main switch our IT guy (Dave) said that it shows on his system as DHCP for the three missing ip addresses. It should be showing bootp like the rest. Why would bootp say it successfully made the relation and then still be DHCP? Have you experienced anything like this before? Really confused

Hi Terry,

I have had an issue similar to this before, but with different hardware.

I was using Flexlogixs PLCs, with a Hirschmann switch.

I changed the switches over to Siemens Scalance switches, and the problem went away.

Cheers

Mark

Something you said "I use bootp to make the relations and for each one I enable the bootp"

The usual cause of lost IP address is that BootP is left enabled and the power is cycled. This is how it is supposed to work. Once you set the IP address using BootP, disable BootP if you want the IP to be retained.

Terry,

if the bootp and dhcp enable bits in the processor configuration file are enabled, the processor will loose their ip address everytime you loose power because they are looking for the dhcp server to assign an address.

go into your channel configuration - channel 1 and assign a static ip address and subnet mask to what you want.

that way, when they loose power, they keep their ip address and rslinx will also be able to see them without making any changes.

i may not have stated this correctly, so double check what boxes you have to have on.

regards,
james

In the BootP server, after your relation successfully shows up in the lower window, highlight it and click the disable BootP button...It will say command successful at the bottom. That will retain the IP address.

Or once you use the relation and the IP is set, you can go online, go to channel configuration and disable BootP there....You have to click SET or APPLY (don't remember on SLC) for it to take.

Thanks guys. I like James suggestion. I'm going to connect directly to each of the missing PLC's and configure the ip in the channel configuration. Hopefully they will keep their ip addresses. I like it a back door way. Great idea.
Cheers

You still have to use BootP to initially set the IP so that you can even connect via ethernet, unless you're connecting serially first. Just understand, unless you disable BootP either via BootP server utility or via the channel configuration, you can assign an IP address until you're blue in the face, and it will lose it on next power up.