When you post questions about configurable instructions like the MSG instruction, it helps a great deal to post the details themselves, rather than your assessment of the details. In this case the actual IP addresses and the IP configurations of both the SLC-5/05 and the MicroLogix 1100 would be great.
The SLC-5/05 has the ability to communicate both using the older A-B Ethernet protocol, called CSPv4, and the new EtherNet/IP protocol that the MicroLogix 1100 uses.
When you configure a message to a MicroLogix 1100 (or a ControlLogix, for that matter), you must use the "Multi-Hop" configuration in the MSG instruction setup. When the target is a ControlLogix you can specify the Slot number of the controller. When the target is a MicroLogix, set the slot number value to 0.
Your SLC-5/05 also has to be of a firmware revision that supports the newer protocol. If the SLC-5/05 has the 10/100 Mb/s Ethernet port, it definitely also supports EtherNet/IP. Older 10 Mb/s only controllers need to have their firmware checked; I think that EtherNet/IP was added about 10 years ago in OS501 FRN 5, but I'd have to verify that.
