Studio 5000 PLC - PLC Communication

[MagMonk]

I am hoping to use a MSG instruction to communicate between two CompactLogix controllers and was wondering if the Ethernet connection built into the processor will allow communication or if an ethernet module is necessary. Both PLCs will be plugged into an ethernet switch and networked through said switch.

 

[joseph_e2]

As long as the PLCs are on the same physical network and have unique IP addresses that are properly subnetted, they can MSG back and forth.

 

[alan_505]

You can also set up Produced/Consumed tags to use between the PLC's, to do this you will need to add the respective PLC's into each others IO trees, and then create your tags in each PLC, note they must be identical in each PLC, check the user manual for more information.

 

[MagMonk]

Okay great, so no Ethernet module would need to be added! Also do I not always need to add the other PLC to the IO tree when using the MSG instruction?

 

[dmroeder]

You do not need to add anything to the tree to message. The only advantage to adding the PLC to the tree is that the path is easier. I never add PLC's to the tree if I'm only messaging.

 

[alan_505]

Most CompactLogix are restricted to the onboard ethernet port and you cannot add another Ethernet module, the only exceptions that I know of are the 1768-L43 and L45.

The only time you really need to add them to the IO tree is if you are going to use Produced/Consumed data.

 

[BachPhi]

The only time you really need to add them to the IO tree is if you are going to use Consumed data.

 

[Jeev]

A housekeeping note - If you are using MSG instructions, either use read on both sides, or document the use of write on both sides (Who, what and where). This way someone not familiar with the program/system.... or a future you doesn't need to waste time figuring out where or what is magically changing the values of the tags.

 

[robertmee]

A housekeeping note - If you are using MSG instructions, either use read on both sides, or document the use of write on both sides (Who, what and where). This way someone not familiar with the program/system.... or a future you doesn't need to waste time figuring out where or what is magically changing the values of the tags.

Very good suggestion. I don't allow any writes via MSG ever. Only reads.