Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 340)

340 Publication 1756-UM009C-EN-P - December 2010
Appendix C Use Ladder Logic To Perform Run Time Services and Reconfiguration
This prioritization allows input channels to be sampled at the same frequency
and the process alarms to be unlatched in the time between sampling and
producing the real-time input data.
One Service Performed Per Instruction
Message instructions will only cause a module service to be performed once
per execution. For example, if a message instruction sends a service to the
module to unlatch the high high alarm on a particular channel, that channel’s
high high alarm will unlatch, but may be set on a subsequent channel sample.
The message instruction must then be re-executed to unlatch the alarm a
second time.
Create a New Tag This section shows how to create a tag in ladder logic when adding a message
instruction. Ladder logic is written in the Main Routine section of the
RSLogix 5000 software program.
Follow these steps to create a tag.
1. Start the RSLogix 5000 software program and open an existing I/O
project or create a new one.
2. On the Controller Organizer, double-click MainRoutine.
Expand MainProgram to see Main Routine as a sub-menu item.