Ethernet IP Module Q??????

Can you guys tell me if I can take an Ethernet IP module that it has an IP address already setup and take it to any controlLogix PLC rack I have and put it on the rack to talk to the PLC via Ethernet.

Or do I have to connect to the PLC via serial and configure the Ethernet IP module on the configuration hardware before I can use it to talk to the PLC though Ethernet.

The first part is correct.

All ControlLogix EtherNet/IP modules save their IP port configuration (IP Address, Subnet Mask, Default Gateway) onboard the module itself.

These are not automatically configured or over-written by anything in the controller.

You can intentionally write special MSG instructions to re-configure an EtherNet/IP module programmatically, but that is an advanced method and not commonly done.

This is in contrast to the SLC-5/05 and MicroLogix 1100/1400 and PLC-5E controllers. In those control platforms, the IP address and port configuration are part of the user program in the PLC itself.

Thanks Ken. So in essence I can have a ControlLogix EtherNet/IP modules already configure and I can bring it to all the different controlLogix racks I have throughout my plant and as long as I have an opening on the rack I can connect to the PLC using the ControlLogix EtherNet/IP module.

Now, does this also apply if you were to replace a ControlLogix CPU module on a rack. For example will this function If I lost the CPU and I need to put a new one, can I use the ControlLogix EtherNet/IP module to talk to the new CPU and download a program via Ethernet instead of serial.

In short: Yes and yes.

It's pretty common to keep a spare 1756-ENBT configured for the an address that's part of your benchtop or shop network. When you have to connect to a ControlLogix that has a different network and you don't have time to figure out an available address and reconfigure your PC, you just insert that preconfigured 1756-ENBT and get to work.

You can put a ControlLogix CPU into any slot of a chassis and download to it via a 1756-ENET/ENBT/EN2T.

If the controller is new out of the box you will need to load firmware into it before you can load a user program, but you can definitely do that over Ethernet and the backplane rather than through the on-CPU serial or USB ports.

Thank you so much for the clarification.

Ken Roach said:

The first part is correct.

All ControlLogix EtherNet/IP modules save their IP port configuration (IP Address, Subnet Mask, Default Gateway) onboard the module itself.

These are not automatically configured or over-written by anything in the controller.

You can intentionally write special MSG instructions to re-configure an EtherNet/IP module programmatically, but that is an advanced method and not commonly done.

This is in contrast to the SLC-5/05 and MicroLogix 1100/1400 and PLC-5E controllers. In those control platforms, the IP address and port configuration are part of the user program in the PLC itself.

Click to expand...

Ken,

This may not be really relevant now, I doubt anyone is still using them, but I believe the old 1756-ENET modules lost their address when you removed them from the rack (they certainly did for us) but the newer 1756-ENBT do not (I havent personally worked with the EN2T, EN2TR, EN3T or EWEB modules so I cannot comment). I´m not sure if this was a faulty module or if this was a problem with the 1756-ENET.

Regards
Ian

Good point, Ian.

I recall the same behavior with the first firmware revisions of the 1756-ENET module (the original 10-megabit module with no scrolling display), where it would reset the IP configuration if the module was placed in a different chassis slot. I think that was changed by 1999 or 2000.

So I should not have said "all" modules. I wonder if we can hyperlink to footnotes....