Safety Modules Owner manual

78 Rockwell Automation Publication 1791ES-UM001D-EN-P - May 2013
Appendix A Get Diagnostic Status from Modules by Using Explicit Messaging
2. Use the CombinedInputStatus bit to detect if one or more of the I/O
points on the module have a fault.
• If any input status bits go to a value of 0 (0 = bad; 1 = good), use an
explicit message to determine which individual data points have
faulted.
• Note that you can use the second rung to read the status on mode
transition and once a fault is detected, continue reading until the fault is
corrected.
• Place these rungs in the standard task.
See the figures that show the MSG instruction parameters for reading
Instance 869 from the 1791ES-IB16 module. See Appendix
C of this
manual for a layout of possible instances.
Instance 869 (365 Hex) is 7 bytes in length, so the Destination Tag
IB16MSGdata must be at least 7 bytes in length to hold this data. The size
is DINT[2] or 8 bytes.