SLC 505 loses IP address

High all,

We have upgraded to the SLC 505's in order to better instruct our students. I set up a standard 192.168.0.x scheme and have used Rockwell's Bootp server to assign addresses. I disable DHCP/Bootp afterwards. This seems to work for a while but after a few power cycles, the modules lose their address.

I read some of Rockwell's manuals suggesting the setting up of the Channel 1 configurations. I have done this also. The method I used was to set up a connection using the serial cable, then configured the channel (MAC address, IP address, and disable Bootp), then downloaded to make sure new channel config was written. When I come back after the weekend some of the modules still lose their IP address.


The problem is that in our lab these machines may be turned off for weeks at a time as we teach other classes in it. When they power back on, we cannot PING the address. Perhaps I have missed a step or done it all wrong.


Of course we can always run lab over the serial cable but showing the versatility of Ethernet would be wonderful to incorporate into our lab.

THANKS for your help and sorry if I posted incorrectly, this is my first time!

are you sure the eprom batteries on the processor are good?

The boards are brand new so I assume yes. I also receive no battery warning light on the module.

If a user downloads an offline file and selects the "Overwrite com channel settings" it will wipe out what every you setup. May be a training issue for the students to not overwrite that.

Not really helpful in solving your issue, but...

I'd personally see that trait as a good thing in a strange sort of way. Because setting IP addresses and getting initial comms working with new or unknown PLC's is quite often one of the hardest parts of learning to be a PLC programmer. If your students have to learn how to do that, it can only be good for their experience.

Of course, if the same student is having to do it over and over again on the same PLC they'll likely be getting a bit peeved, so I know it's still not a great thing

Does the IP change back to default? Or just some other random IP?

Sounds like you either don't have the PLCs configured to maintain a static IP address, you have dead batteries, or you're overwriting your port configurations with a program download.

Well considering I cannot ping it, I dont know what IP address is has. I could look on the switch but I usually just connect it with a serial cable and just reassign it.

When I have the issue, and I finally get it back online the BOOTP check box is selected again in the channel 1 configuration. I deselected it many times from this area and have deselected it from the BOOTP server also. Is there a way to "burn" in an IP address or someway to make it more permanent?

Maybe your students are propagating a cute little trick on you by changing the BOOTP setting in the PLC before they shut down?
I have never experienced this sort of problem on equipment that I have built and not heard any other programmers complain of the same thing. Nor have any of my customers mention anything of this sort.

No one is playing tricks. I believe it is something I am doing wrong.

What you are doing is correct. It is not uncommon for the BootP server to fail to turn off BootP even though it reports it has done exactly that.

In my experience, using RSLogix 500 to write the channel configuration is the most sure way to set the IP configuration and the PLC should remember that info indefinitely.

The BootP utility is quirky at best. Just yesterday, I had it do about the same thing to me with a ML1400 I had sitting on the desk. I did not want to dig out my serial cable so I finally just set the darn thing with the silly keypad after giving up on the BootP utility.

With a 5/05, I would have gotten out the serial cable and downloaded a dummy program with the channel configurations I wanted and that has not let me down yet.

If there are memory modules installed in the suspect SLCs, that can be your problem. If you want to keep the memory modules installed, then get the settings you want, go online and "Store to EEPROM" (under the menu bar Comms, EEPROM).

I will go tinker some more.

OkiePC said:

What you are doing is correct. It is not uncommon for the BootP server to fail to turn off BootP even though it reports it has done exactly that.

In my experience, using RSLogix 500 to write the channel configuration is the most sure way to set the IP configuration and the PLC should remember that info indefinitely.

The BootP utility is quirky at best. Just yesterday, I had it do about the same thing to me with a ML1400 I had sitting on the desk. I did not want to dig out my serial cable so I finally just set the darn thing with the silly keypad after giving up on the BootP utility.

With a 5/05, I would have gotten out the serial cable and downloaded a dummy program with the channel configurations I wanted and that has not let me down yet.

If there are memory modules installed in the suspect SLCs, that can be your problem. If you want to keep the memory modules installed, then get the settings you want, go online and "Store to EEPROM" (under the menu bar Comms, EEPROM).

Click to expand...

I agree. Ive never had much luck with the bootp utility.

Would you mind taking a picture and posting it of

the screen where you are setting the IP address

under the channel configuration tab.


Thanks