Interconnecting Systems Via Ethernet Verify my setup?

Hi! I am about to interconnect two PLC systems VIA an Ethernet connection, and I just wanted to ask if everything about it sounds "right" to everyone.


System #1 - is a CompactLogix L33ER with remote I/O VIA a (Ethernet)1794-AENT and also has a (Ethernet) Panelview, a (Ethernet) VFD and a Ethernet connected server that collects data from it. The IP address of this system is 172.16.10.XXX

System #2 - is a CompactLogix L33ER with remote I/O VIA a (Ethernet)1794-AENT and also has a (Ethernet)Panelview, with no other Ethernet devices. the IP address of this system is 12.4.0.XXX

Since System #2 has the lease amount of devices connected to it, I figured I would change that system to accommodate System #1
Is this as simple as changing the IP address of the L33ER, the Panelview, and the 1794-AENT, to match the first three octets of System #1, as long as I use rslinx and a command prompt "ping" command to make sure the last octet is available? I imagine I have to re-setup panelview communications in FTV studio correct?


then just plug and play?

You guys are the best! :site:

You're pretty much on the money. One word of caution - just because you get no response from a ping, doesn't mean the address is free. It might be in use by something that's not switched on right now, like a programming PC or a VSD that's isolated for maintenance. Or a device might just not respond to a ping right now because it's overloaded or has some funny communication settings going on. You'd be best to do a thorough audit of the system and identify anything that ever connects to that segment of the network, and what addresses each device has. Document it all on a spreadsheet - going forward, you should have a spreadsheet anyway.

After that:
- Change the IP addresses of the PLC and 1794-AENT using RSLinx. You will need to power cycle to get the new addresses to "take".
- Change the IP address of the 1794-AENT within the PLC program, and re-download. I'm not 100% sure whether you can change an IP address in that manner, or whether it'll make you delete and re-add. If it's the latter, you'll also have to re-configure any I/O modules attached to your 1794-AENT, so make sure you've documented all of the settings first. Take a backup of your PLC program before you start, so you can go back and look if required
- Change the address of the PVP on the terminal itself. Post back if you need any help with this part
- Modify the PVP program to point to the new PLC address. Again, you might have to delete and re-add rather than just change. Make sure you modify both the design and runtime communications path. Then download the modified program back to the PVP and test

With the last step, it is technically possible to just change the shortcut path on the PVP itself - but then you'll only run into problems 6 months down the track when you make a change to the program and download it, overwriting your updated comms setting. If you're taking the time to do it properly, then do it properly all the way.

There are also other options available like using NAT devices or a gateway to connect the two networks together - but if changing the IP's is a viable option for you, and makes sense within the context of your wider plant network, it's definitely the way to go. There's a little bit involved in getting it changed over, but at the end of the day you end up with a much, much simpler network to work on.

Good luck!

Hey Thanks! I feel much more confident in doing this now! Surprisingly I totally understand everything you just said.

Thanks Again!

Brilliant! My englishing is gooder today than some other days!

Just had another thought - check for managed switches on the network, because they will have IP addresses too - and *might* need some configuration changed if you're changing IP's.

Following on ASF's tips, some devices (although I haven't seen them in industrial environments) are configured not to reply to ping requests.

If you have the time, I believe NMAP is a great tool to audit networks despite its full functionality being overkill for most control system networks. It is now available for Windows and with a GUI too, although you may need to deactivate your anti-virus if you have any.