EDWARDS SYSTEMS TECHNOLOGY IRC-3, Programming Manual, Page: 36 / 284

1.30 Programming Manual
Priority 99
Priority 99 Set and Reset also have special functions associated with
them. Priority 99 latches the output to either the Set or the Reset
condition. An output, when latched, will not restore when the zones
causing their change of state have restored. This type of relay priority
may be used for the following applications:
1. Amplifier backup switching.
2. Security circuits.
3. Fan control circuits to prevent feeding the fire.
The following points must be considered when using relay priority 99:
1. An output that is Set by priority 99 can only be restored by a Reset
priority 00.
2. An output that is Reset by priority 99 can only be Set by a priority
99 or 00.
3. A Set priority 00 will override a Set priority 99, which changes it
from a latching output to a lowest priority non-latching output.
4. A Reset priority 00 will override a Reset priority 99, which changes
it from a latching output to a lowest priority non-latching output.
Examples #6 and #7 may help you understand this priority level.
Example #6
Input Status Programmed
Event
Output
Status
Output
Priority
Output
Counter
normal — restored — —
Iactivate-01> Output Set-08 ON 08 1 (Set)
Iactivate-02> Output Set-99 ON 99 2 (Set)
Irestore-02 ON 99 2 (Set)
Irestore-01 ON 99 2 (Set)
Iactivate-03> Output Reset-00 OFF 00 1 (Reset)
Irestore-03 restored — —
The following items should be noted in example #6:
1. The highest priority Set 99 latched the output and set the output
counter to a latched condition.
2. The Set output priority 99 was unlatched by priority 00 Reset.
Example #7
Input Status Programmed
Event
Output
Status
Output
Priority
Output
Counter
normal — restored — —
Iactivate-01> Output Set-99 ON 99 1 (Set)
Iactivate-02> Output Set-00 ON 00 2 (Set)
Iactivate-03> Output Reset-01 OFF 01 1 (Reset)
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