[BigEllT]

I have a RS Logix 1756-L63 PLC running with 2 Panelview Plus 600 Display units. The ethernet card is communicating to the 2 HMI units. I need to change the IP address of the 1756 ENBT/A module from 192.168.0.1 to 192.76.251.160. If I lose communication with the PVP 600's for a while, it is not a problem. However I must not stop the PLC running. What is the best way to do this. I have only ever configured a card with BootP when installing a new system. Thank you

[Joe E.]

Is anything else talking to the PLC through that ENBT besides the HMIs? If not, I see 2 ways to do this without causing issues:

1) Take a compatible spare off the shelf, configure it, and then swap them. This will involve the least time yelling and swearing with the cabinet open ;)
2) You could use the BOOT/P utility and just unplug the module from the chassis to reboot it as needed.
For either method, you should check in the PLC project to make sure that the ENBT isn't configured to fault the processor in case of failure (probably isn't if it's just servicing HMIs and the programming PC)

If the ENBT is in the project, you can change the IP address there, but I'm pretty sure you have to do it offline and download, which stops the PLC.

[BigEllT]

Thanks Sparky

I am of the same opinion that I would need to stop the PLC to download the project, but I will try the BootP configuration and pull the card. I do not think any other devices are communicating with the IP card. But thanks for the reminder to check the PLC response if the IP card stops running.

[dmargineau]

BigEllT, on 20 September 2012 - 12:17 PM, said:

Thanks Sparky

I am of the same opinion that I would need to stop the PLC to download the project, but I will try the BootP configuration and pull the card. I do not think any other devices are communicating with the IP card. But thanks for the reminder to check the PLC response if the IP card stops running.

What firmware revision are you running on the CLX controller?
If it is 17 (or higher) you could add/edit 1756-ENBT modules Online in Run Mode.
Of course , if you are editing the same ENBT bridge you are using to connect RSL5K to the controller, you will lose the PC-CPU communications when "applying" the edits...

[JohnM]

An important thing missed here is that you will need to change the address in the HMI AND also create new MER files to run in the HMI pointing at the new PLC address. Just changing the address in the ENBT can be done online using RSLinx. The address in the project tree is not loaded anywhere it is just good for your records. I have changed ENBT addresses on line before and the PLC keeps on running but you need to have a plan for your HMI. You also need to know if you have any tags communicating with other PLCs as changing the address will break that link too.

[BobLfoot]

JohnM, on 21 September 2012 - 08:38 AM, said:

You also need to know if you have any tags communicating with other PLCs as changing the address will break that link too.

[HINT HINT]
Opening the ENBT webpage with a browser and checking the connection list can help prevent a world of trouble.
[/HINT]