cip connection and MSG connection

i want to comunicate between 2 PLcs so i want to use MSG instructions
i understand that ther is a limit, so if my controlLogix limit to 128 CIP connection that means i can activate together only 128 MSG instructions?

Based on my reading:

The limit on CIP connections are for persistent connections such Produce or Consume tags. The limit of CIP connections depends on the type of communications card (EN2T supports 256, ENBT supports 128)

So you can only have that limit of CIP connections active at the same time.

A MSG instruction can be programmed to be "one time only."
You can also choose to cache the connection (as a CIP connection) and you can leave it open, which would count toward your CIP limit.

That said, you can certainly have more than 128 or 256 MSG instructions as long as they all aren't executing at once, or you have too many cached connections.

Ken can probably shed more light on this than I.


I recommend reading these, they can probably answer most of your questions.

http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm012_-en-p.pdf

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1756-rm094_-en-p.pdf

b_e33 has been shotgunning the Forum this morning with questions about maximum connections and simultaneous messages, and I'm not going to answer every thread he starts. My answers typically take me 20 to 100 times longer than his questions take him, and I'm out of resources.

My advice is to get the communications working between his two controllers before starting to worry about how to handle hundreds of MSG instructions.