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SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
MCS--4200/7200 Multi--Channel SATCOM System
E. Monitoring and Testing Functions
(1) General
(a) The declaration of an inactive input bus takes precedence over declaration of
one or more data word failures against the LRU driving that bus (i.e., if the bus is
inactive, additional logging and reporting of low-rate failures of individual data
words on that bus are precluded). The failure and recovery criteria is set to make
sure individual data word failures are not declared when the bus is inactive. This
is typically done by setting inactive bus failure criteria (e.g., three seconds) to be
faster than word update rate failure criteria (e.g., five seconds), and inactive bus
recovery criteria (e.g., two seconds) to be longer than word update rate recovery
criteria (e.g., one second).
(b) Unless an LRU providing ARINC 429 data declares itself to have failed, a fault is
declared against that LRU when the ARINC 429 data is faulty. This is determined
by checking (as appropriate for each word) for data inconsistencies, data
out-of-range, uses of undefined or reserved values, and occurrences of the
failure warning state in the sign/status matrix (SSM) field.
(c) Two basic types of failure detection testing performed are: functional tests and
continuous monitoring (CM). The purpose of functional testing in the form of
power-on self test and person-activated self test is to exercise the equipment in a
manner as closely as possible to its normal operation. Failures detected during
functional testing are declared to be current failures until a subsequent functional
test shows the failure condition has recovered.
(d) The purpose of continuous monitoring is to test the equipment in a nondisruptive
manner while it is performing its normal operations. Such testing usually includes
monitoring the power supply voltages, temperature sensors, bias currents, input
bus activity, buffer overflow, input data failures, etc. This testing can also include
abnormal failures that cannot be tested as part of the functional testing, such as
protocol failures, processor instruction traps, data loader problems, etc.
(2) Power-On Self-Test
(a) General
1
The power-on self-test (POST) is a series of functional tests for individual
LRUs; each MCS LRU performs its own internal POST upon a cold start. A
cold start is defined as the response of an LRU where no retention of any
previously stored information in any volatile memory is assumed. The power
supply provides signals to help an orderly power-down and power-up
process for the LRU during power interrupts of any length. Primary power
interrupts of less than 5 milliseconds duration have no effect on system
operation. For primary power interrupts longer than 5 milliseconds and up to
200 milliseconds duration, the LRU maintains normal operation, except the
RF transmit and receive processes do not need to be supported in any LRU
during this interval. For primary power interrupts greater than 200
milliseconds duration that causes normal operation to cease, the LRU
performs a cold start following restoration of primary power.
Honeywell International Inc. Do not copy without express permission of Honeywell.
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15 Jul 2006
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