Micrologix 1100 to Micrologix 1100 Communications

Sorry I'm a beginner to the PLC world. I've managed to make my way through programming a few PLC and HMI's by reading some of the posts here, which are very helpful. But I'm currently having trouble figuring out how two Micrologix 1100's are communicating with each other. I have a Micrologix 1100 (PLC 1) and a panel view 1000 connected to a Ethernet switch in one building. I then have a Micrologix 1100 (PLC 2) connected to a Ethernet switch in another. The HMI gets readings from both PLC's, but when i look in the communications of the HMI I only see PLC 1. When I have a input triggered from a well float on PLC 2 it goes to a OTE N7:37, then opens a XIO N7:37 in PLC 1 so I know they are linked. I want to build this on my bench and make changes before I do anything in the field. Don't want to screw up anything.

Any help would be appreciated.

Look for MSG instructions in either PLC (perhaps both) reading or sending registers including N7:37. If you get very confused zip and post both programs.

I have used Micrologix 1100s which were linked by messaging before.

To expand on Bernie's post, the important thing you need to understand is that "messaging" between your PLCs can be initiated at either end, and it is not necessary to have a corresponding Read or Write in the other PLC.

One PLC can be READing from the other, or one PLC can be WRITEing to the other, both scenarios are usable.

And to add to daba's post, it's generally good practice to always READ rather than WRITE wherever possible. If you WRITE to another PLC, there's nothing in the written-to PLC's code to indicate what it is that keeps changing the data, or where it's coming from. Better to have each PLC read the other, and then you can see the MSG instruction that's populating your data.

Of course, there are always exceptions

Got it...Thanks for the help