Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 146)

146 Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Appendix A Get Point Status from Modules by Using Explicit Messaging
2. Use the CombinedStatus bit to detect if one or more of the I/O points on
the module have a fault.
• If the CombinedStatus bit goes to a value of 0 (0=bad, 1=good), use an
explicit message to determine which individual data points have
faulted. Use the CombinedStatus bits to condition your msg rung as
follows.
• 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.
This figure shows the MSG instruction parameters for reading
Instance 786 from the 1791DS-IB12 module.
In this example, we created a UDT from the destination type.
• You can find the UDT called Assembly786_1791DS_IB12 in an ACD
file. This UDT is based on the Assembly786 for the 1791DS_IB12
module.
• There are other assemblies in the EDS file that can be used, but this one is
the most inclusive.
• Make sure the Communication Path is set to the correct module.