CMUip-2212 Cabinet Monitor Unit
Operations Manual
Eberle Design Inc.
Page 10
2.14.3 DATAKEY MEMORY DIAGNOSTIC
This test will verify whether the non-volatile Datakey contains valid data. The routine will
perform a check on each nonvolatile memory element at power-up and whenever read and
make a comparison with a 16 bit Frame Check Sequence (FCS) procedure defined in
clause 4.6.2 of ISO/IEC 3309. Invalid data may result from corrupted Datakey contents, an
invalid FCS calculation, invalid parameter values, or a Datakey Protocol Version
incompatibility.
The Datakey not present will cause a LFSA and illuminate the DIAGNOSTIC indicator if the
DOOR SWITCH FRONT input is sensed as not active (door closed). The DIAGNOSTIC
indicator will flash at a rate of 2Hz if the Datakey is not present when the DOOR SWITCH
FRONT input is sensed as active (door open).
2.14.4 INTERNAL MPU MONITOR
The CMUip-2212 will monitor the operation of its microprocessor with an independent
circuit. At a minimum, the monitoring circuit will receive logic state transitions at least once
every 50 milliseconds from the microprocessor. When the logic state transition is not
received for 500 milliseconds the monitor circuit will force a LFSA-R and illuminate the
DIAGNOSTIC indicator.
2.15 RECURRENT PULSE DETECTION
This error detection function supplements the normal Conflict, Multiple, and Lack of Signal
monitoring algorithms for sensing faults that are intermittent or pulsing in nature. The RMS
signal detection algorithm is designed to filter out short term transients commonly found on
the electrical service and provide noise immunity against false signal detections. The
Recurrent Pulse detection function is designed to respond to fault conditions that are
intermittent in nature and do not meet the continuous timing requirements of the normal
detection algorithms, yet may still produce improper signal displays. These input conditions
are differentiated by their longer time constant and fault response times.
The figure below shows a simple example of a recurrent Conflict fault. Channel 2 Green is
detected active due to a malfunction of the load switch that caused the output to
A
flicker
@
On for 100 ms approximately every 200 ms. Because normal Conflict detection requires a
continuous fault of at least 350 ms duration, this event could go undetected. The Recurrent
Pulse detection algorithm will combine these pulses into one event and trigger a Conflict
fault once the longer recurrent timing threshold is exceeded.
When triggered by a recurrent fault condition, the Signal Monitor will enter the fault mode,
transfer the Output relay contacts to the Fault position, and illuminate the appropriate
CONFLICT, MULTIPLE, or LACK OF SIGNAL indicator. The unit will remain in the fault
mode until reset by the Reset button or the External Reset input. Fault response times will
vary depending on the pulse width and frequency of the recurrent inputs, but will range
from 1000 ms minimum to 10.4 seconds maximum. Recurrent Pulse detection can be
disabled with the SEL1 option jumper, see Section 2.15.1.
