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Issue 5 - September 2006
Page 24 of 65
1
Logic Supply B power fail fault
2
Logic Supply C power fail fault
3
Reserved
4
Reserved
5
Reserved
6
Field power fail fault
7
Output discrepancy error
8
Reserved
9
Reserved
10 Reserved
11 Reserved
12 Reserved
13 Reserved
14 Reserved
15 Reserved
Table 4 Piano and Analogue Fault Flags
The following alarm contacts are available and can be wired into the system for use by the
application logic.
Power supply fault
2 off, any system or field power supply
System cabinet over-temperature
Cabinet high temperature \ ventilation
alarm, if fitted.
Fuse failure
Any fuse failure, grouping being application
dependent.
Watchdog monitoring alarms
3 off inputs monitoring the external
triplicated watchdog.
Table 5 System Alarms
3.5.9 Automatic Diagnostic Action
Certain actions, dependent on configuration, must be taken by the application logic on the result
of certain error flags and combination of error flags.
3.5.10 Without Time Constraint Configuration
If a system is configured without time constraint (eg each critical process parameter is controlled
by at least two separate digital output modules), then only annunciation of diagnostics is
required.
3.5.11 With Time Constraint Configuration
If a system is configured with time constraint (eg any critical process parameter is controlled by
a single TMR digital output module) then Global Output bit is used to start a timer equal to the
time constraint of the Output Module and when this timer has elapsed an ESD command should
be instigated. Example shown in Appendix 1
3.5.12 Long Process Time Constraint System
For systems controlling a process that has single inputs configured using the single slot hot
repair facility then the "Single Slot Off-Line" error flag must be used to start a timer equal to the
process time constraint. When this timer is elapsed an ESD command should be instigated.
3.5.13 Initialisation Flags
This flag indicates a wrong configuration of I/O modules or an I/O module or modules missing.
Although these errors are inherently fail safe (eg when an on-line output module is removed its
outputs automatically fail-safe).