Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 79)

Command Initiation, Execution, and
Monitoring
Chapter 7
7-7
Even though the FAULT bits are continually reset with this method, their
usefulness must not be overlooked. The section titled “REMOTE/FAULT
Bit Monitoring” outlines a useful method to monitor FAULT bits and
control an output indicator based on FAULT bit status.
In some applications, it may be useful to send a command continuously
between stations. With the example of Figure 7.3, this can be
accomplished by eliminating the EXAMINE OFF instruction for input
11111 in the second rung. This would cause the command to be sent
continuously as long as input 11111 remains ON.
Transition
The transition of an input device from ON to OFF and from OFF to ON
can be used to LATCH the START bit. This allows a command to be sent
each time a condition changes state. Figure 7.4 shows example rungs for
this type of command initiation.