CMU-212 Cabinet Monitor Unit
Operations Manual
Eberle Design Inc.
Page 8
will be recognized when both the POWERDOWN and NRESET signals are False (low) for
greater than 100 ms or the AC+ RAW voltage is less than 82 +/- 2 Vrms.
The 24VDC Monitor function (section 2.1) will be disabled while the POWERDOWN signal
is in the False state. The 24VDC FAIL indicator will flash at a 2Hz rate (section 4.1.2).
2.12.1 AC+ RAW LEVEL SENSE
The CMU-212 will monitor the AC+ RAW input and AC+ RAW inputs reported by each
AMU-214. When any AC+ RAW voltage is less than the AC Line Dropout voltage (section
5.1) for greater than AC Line Level Sense timing (section 5.2) the CMU-212 will cause a
NFSA. Once NFSA has been set, the POWERDOWN and NRESET signals will not be
monitored until all AC+ RAW voltages have exceeded the AC Line Restore voltage (section
5.1).
2.12.2 POWER INTERRUPT
The CMU-212 will disable monitoring of the +12VDC and +24VDC power supply inputs
when either the POWERDOWN or NRESET input is False (low). When the POWERDOWN
and NRESET signals are both False (low) the CMU-212 will cause a NFSA.
2.12.3 POWER RECOVERY
When the POWERDOWN input is True (high) and the NRESET signal goes from False
(low) to True (high) the CMU-212 will begin timing the programmed Minimum Flash
Interval. During the Minimum Flash Interval the CMU-212 will be in NFSA.
2.12.4 POWER UP
Following initial application of AC+ RAW voltage the CMU-212 will maintain a NFSA until
the POWERDOWN input is True (high) and the NRESET signal goes from False (low) to
True (high). The CMU-212 will then begin timing the programmed Minimum Flash Interval.
During the Minimum Flash Interval the CMU will be in NFSA.
2.12.5 MINIMUM FLASH INTERVAL
During the Minimum Flash Interval the CMU-212 will be in NFSA. The Minimum Flash
Interval will be programmed in the Datakey between the limits of 6 seconds to 16 seconds
with an incremental adjustment of 1 second. The CMU-212 will not set a FSA during the
Minimum Flash Interval.
2.13 FIELD OUTPUT CHECK
The Field Output Check is a continuous verification that the field signal output states set by
the ATC are properly driven to the signal loads and correctly sensed by the AMU-214 and
CMU-212. It is an enhanced function made possible by the Serial Bus #1 communications
between the ATC and CMU-212. The CMU-212 will receive a Type 61 message from the
ATC that contains an image of the controller output commands to the load switches. When
a fault condition triggers the CMU-212, the Type 61 message information received while
the fault condition was being timed will be used by the CMU-212 to determine whether the
sensed field signal input status corresponded to the ATC output commands. This
diagnostic information may then be used to isolate whether the fault condition was caused
by an ATC malfunction or a failure in the load switch and/or field wiring.
The Field Output Check function is enabled for each channel input individually and provides
two modes of operation, Field Check Mode and Field Check Status.
2.13.1 FIELD CHECK MODE
The CMU-212 will compare the active states of the field signals with the states reported by
the ATC in the Type 61 frame. When a mismatch is detected for less than 700 milliseconds
