Rockwell Automation 1771-PM , D17716.5.18 U MNL 1771-PM CLUTCH/BRAKE MOD - Manual (Page 41)

Voting Processor Firmware
Chapter 5
5Ć2
PM modules continuously monitor your clutch/brake system for a trip or
stop condition. Either condition halts and/or prevents press operation.
For this condition PM modules remove solenoid power by
Trip Removing power from field wiring arms
Stop Turning off outputs from the output module
controlling the solenoids
Trip condition - A PM module turns off swing arm output power by
de-energizing its seal relay output when it detects these trip conditions:
lost communications with the other PM module for 100ms
a change in wiring of operator stations 1 thru 4
a short or open solenoid triac
short or open solenoid
feedback [1] connections are wired but not configured
feedback connections are configured but not wired
feedback signals are not working correctly
[1] feedback from valve stem switches, air pressure sensors, and motion detector contacts
Whenever a PM module detects a trip condition, it:
trips power to the wiring arms of the I/O chassis
sets rack fault bits
stops communication with the PLC
If programmed to monitor rack fault bits, the PLC sees the clutch/brake
I/O chassis as faulted until both PM modules verify that power to wiring
arms has been removed. Then they resume communications
automatically.
Stop condition - A PM module stops the press or prevents it from starting
by turning off output triacs to solenoid valves when it detects stop
conditions such as:
lost communications with the other PM module for 50ms
lost communications with the PLC for one second
cam limit switch signals out of sequence
barrier guard opened during continuous mode
This is described further in Chapter 7, Diagnostic Message Codes.
Fault Monitoring