Hi all,

I have a CompactLogix L32E PLC communicating to a VB program via RSLinx DDE, on an ethernet connection, also a PanelView Plus 1250.

I need to change the IP address of the ethernet port on the PLC, but the PLC is in run, and I won't be able to cycle power, switch to Program mode, or re-download the program, for a least another 12 hours...
I really need to get this done today (scheduling error means I missed the last chance).

I will be changing the PC & PV ip addresses also, to match, so the VB program on the PC and also the PV will loose comms briefly - this is not a problem as long as the PLC doesn't crash, and I can re-establish ethernet comms after the change.

I always assumed it couldn't be done, but looking at the manuals, they don't explicitly say you cannot change it while in run, but they don't say you can either...
I notice RSLinx won't allow me to select Module Configuration of the ethernet port, when i hook up to the PLC via serial (DF1)...
But the module configuration window in RSLogix5000 does not have the IP/subnet/etc boxes grayed out, which would seem to me that I can change them, but the help says that the IP must match the IP address under then General tab, or I could loose communications until I re-download the program.

Anyone know for sure?

TIA
Andrew W

Edit - Were you online when you looked at the port configuration tab? I don't think it is blanked out when you are online. But I will leave the origional post below in case someone else might be able to use it. We use this message instruction for a backplane based DHCP server. What ever ENBT you put into a controllogix chassis at a certain slot, the processor will send a message to that particular slot to set the IP Address. Actually we do the configuration of all our modules from the chassis side on power up so everything is plug and play

You can do it through a message instruction in the ladder. But before we go there go to the Ethernet port of the Compactlogix in RsLinx and right click it and select Device Properties. The IP configuration is there and I don't believe it is blanked out but don't have anything to look at to be sure. If you can wait till tomorrow morning I can check and be sure.

If you can't do it with RsLinx. The values you put in this will need to be in HEX. If you do not understand how do to this please let me know before you do anything.
Create a tag, NewIP data type SINT[22]
Create a message instruction with the following parameters and fire it
Message Type - CIP Generic
Service Type - Get Attribute Single
Class - f5
Instance - 1
Attribute - 5
Destination - NewIP[0]
Select your Ethernet Port as your path

This will read the current IP address and give you the base to work with.
The layout is
0 - IP Address last number
1 - IP Address 3rd number
2 - IP Address 2nd number
3 - IP Address 1st number
4 - Subnet last number
5 - Subnet 3rd number
6 - Subnet 2nd number
7 - Subnet 1st number
8 - Gateway last number
9 - Gateway 3rd number
10 - Gateway 2nd number
11 - Gateway 1st number
12-21 - Just leave these as they are.

After you change you IP in NewIp, change your message configuration to the following and re fire it
Message Type - CIP Generic
Service Type - Set Attribute Single
Class - f5
Instance - 1
Attribute - 5
Source - NewIP[0]
Source Length - 22
Select your Ethernet Port as your path

Just checked and you can change it from RsLogix 5000

Go the the Ethernet ports properties and go to the port configuration tab.
Enter your new IP
Press the set button and let it continue on the warnings
It will kick you offline
Then go to the main tab and change the IP. I really don't know what this one does.
Then change you path For RsLogix to you new path and go back online
This takes approximately 1.25 minutes for me to do

I'm trying to do this to get the current IP only, not modify. How do I convert the HEX data into useful information?

Thanks!

Mike