Allen-Bradley 1756-IB16IF - Perform a WHO to Retrieve Module Identification and Status

228 Rockwell Automation Publication 1756-UM058G-EN-P - November 2012
Appendix C Use Ladder Logic To Perform Run Time Services and Reconfiguration
The Controller Tags dialog box shows examples of the tags created in the ladder
logic, as displayed in the tag editor.
Perform a WHO to Retrieve Module Identification and Status
This ladder logic example shows how to retrieve module identification and status
through a WHO service. In this application, a message instruction retrieves the
following module identification information:
• Product type
• Product code
• Major revision
• Minor revision
• Status
• Ve n d or
• Serial number
• String length
• ASCII string
A full explanation of each module identification category is provided after the
ladder logic application.
IMPORTANT
The ladder logic example in this section uses a user-defined WHO data
structure and a series of Copy instructions (following the Message instruction
in the screen capture) to make the module identification information more
easily understood.