Allen Bradley Ethernet Do's and Don'ts

MSG Manager

Try searching for Message Manager on the Rockwell site. There is a long list of things to not do, especially in Controllogix, if you don't want the MSG's to error. If the MSG errors, it is usually ok to just try again. The main thing is to not have too many MSG's enabled at once. An ethernet connections can only have som many connections enabled at once, including cached connections which stay open.

Start by reading carefully the MSG instruction section of the Instruction Set Reference. It really does include a lot of the information you need.

For your specific application, there's a tested and reliable example posted here:

http://forums.mrplc.com/index.php?download=759

I continue to strongly recommend that start/stop functions be HARDWIRED when you're dealing with MSG instructions from a MicroLogix or SLC to a drive. If you're going to perform all control over the network, use the example and be certain to verify and test all your failure modes.