Rockwell Automation Logix5000 Controllers Controller Information and Status Programming Manual - Manual (Page 38)

Chapter 3 Controller logging
Create custom log entries
You can add custom entries to the controller log using a message instruction. The
message instruction uses a CIP Generic message type and a service type of
Controller Log Add Entry.
The source element of this message should be a tag of a user-defined data type. The
user-defined data type should contain two string members. The controller writes
the first string to the log entry's Description field. The controller writes the second
string to the log entry's Extended Information field.
The following rung of ladder logic shows how to send the message instruction,
followed by the Configuration dialog box of the message instruction and the
definition of the user-defined data type used for the source element.
Example: Send the Message ladder instruction, Controller Log Add Entry configuration dialog box, and Data Type
dialog box
38 Rockwell Automation Publication 1756-PM015F-EN-P – October 2014