I/O configuration problem

Hi every, I have two PLCs both 1756-L55 processors, when I open each of their respective programs in RSLogix 5000, in one I can see the backplane, processor, etc, but the other one looks like this:



I want to be able to communicate between the two PLCs but I can't as either using messages or producing consuming bits instructions state you should have the other PLC added to the I/O configuration of the PLC it's talking to. I can't access the Ethernet part of the I/O configuration like I can in the example below so I can't add the other PLC.



I really can't see what's going on, I tried adding the processor which is in slot 0, but then I get a message saying this slot is already in use, at the moment both PLCs do operate but don't talk to each other

Sorry meant to say both Allen Bradley PLCs

With MSGs you should not need the CPU in the I/O tree, but the controllers need to be physically available to the same network through their backplanes and comms modules. The IP address settings (assuming ethernet route) need to be in the same subnet also.

What do these two CPUs look like when you view them in RSLinx/RSWho?

Also, I think you can used produced consumed, but it sounds like you are filling in the information incorrectly. I have only done produced/consumed once a few years ago, so I should probably let others chime in to give you good instruction there.

Thanks for the reply I'll check now

Which are the IP Addresses of the two 1756-ENBT bridges (KILNS_ENET and Mill_PLC_Ethernet)?
Is there anything "connected" to the 1756-ENBT/A KILNS_ENET bridge subnet?

That's the strangest part the, kilns PLC is connected to another PLC (not the mill one) yet I can't see how given the I/O config looks incomplete

After a second look, I believe the top part of your screenshot is not a chassis containing a CLX processor but a 1756 4-slot chassis without any present controller.
You will have to go and "find" the second L-55.
Could you show us the entire Project Tree for the "alleged" L-55?

That's what I thought too, but I went out to the cabinet and checked, L55 processor and 7 slot rack, also from within RSLogix if you click at the top on the menu at the left hand side it states it's a L55 processor

That's weird...
What revision does the "different" RSL5K project carry?

Here's a pic of the kiln PLC

dmargineau said:

That's weird...
What revision does the "different" RSL5K project carry?

Click to expand...

what revision would you like me to check?

For the "missing backplane" one?

First, an apology: I generally criticize the use of "new/old" or "newer/older" instead of specific Revisions or dates. But I'm going to do that here because I don't have easy access to firmware or software histories or time to do the research. If the exact revisions become important, we'll do a little community research.


The "Kilns" controller is older; probably v16 or older firmware.

RSLogix 5000 originally didn't have a Controller icon in the "I/O tree" view; the Controller whose program you were looking at was inferred to be in control of that chassis, and the Slot number was just set in the Controller Properties. The local Controller icon was added later, just for clarity.

Another feature that was added "later" is the ability to add 1756-series I/O modules to Ethernet networks in RUN mode.

The good news is that you can definitely use MSG instructions to communicate between the controllers by entering in the Path field manually. Having a controller in the I/O tree is just a handy Path definition shortcut when you're using MSG instructions.

Produced/Consumed Tags do require the Producing controller to be in the I/O tree of the Consuming controller, so in your case that will require a shutdown and offline change to the project.

Ken,
It is lower than 16; my 16.30 "test" RSL5K with an L55 provided a backplane.

You guys are great! You're right the Kiln PLC processor is version 12.23.
Glad I can still use messages, thanks again everyone.