Detcon 10C Facilities - Manual (Page 7)

Model 10C
10C Control Module Instruction Manual Rev. 0.0 Page 3 of 14
The SSC settings cannot be monitored nor can they be changed through the FM operator interface. The FM
has its own Alarm configuration and function. The FM takes the alarm conditions from its group of slave SSC
modules and performs a logical-OR to accumulate a residual alarm state. That is, if any alarm state is ON, the
logical-OR of alarms will result in that alarm being ON in the FM. The FM only evaluates the alarm status
given by each SSC. The FM does not evaluate the concentration value – the SSC module compares
concentrations values against Setpoint thresholds and reports the alarm state via Modbus. The FM local alarm
state, being the logical-OR of the SSC alarm states, is displayed on the individual LED annunciators on the
FM front panel.
The Modbus Communications between the FM and each SSC whose Modbus Address is less than or equal to
the Number of Slaves, must be valid or a communications fault will result. SSC Communications Faults are
also Logical-ORed with all the other SSC alarms.
Given the logical-OR result, the resultant alarms can be configured for application to the local on-board relays
(on-board the FM board) to be either enabled or disabled for each of: latching, energized or silenceable.
1.2.1 Latching or Non-Latching Relays
All alarm relays: Alarm 1, Alarm 2, and Fault, can be programmed as Latching or Non-Latching. If an alarm is
programmed to Latch, its corresponding relay and LED Indicator, once activated, will stay activated, until
reset, even if the alarm report from the SSC Slave “clears”. If an alarm is programmed as Non-Latching, the
alarm will not remain activated if the alarm report from the SSC Slave clears.
To configure an FM alarm relay, note that this is a separate configuration from the individual SSC alarm relay
configurations, which may be individually set per SSC module.
Latched alarms do not automatically reset when the alarm clears. The function of resetting latched alarms is
described in the section on Alarm Reset.
1.2.2 Energized or Non-Energized Relay Coils
All alarm relays (Alarm 1, Alarm 2, and Fault) can be programmed as normally Energized or normally De-
Energized. The standard setting for alarms is De-Energized but a relay can be programmed as Energized to
provide application-specific features. For De-Energized relays, the coil will energize in an alarm state so that a
Normally Open contact on the relay will close upon alarm. The opposite is true for Energized relays. The
utility of Energized relay coils is that, if power is lost, the normally closed contact having been held open by
the energized coil, will close. Therefore, loss of power or an unplugged card is distinguishable from lack of
alarm.
To configure an FM alarm relay, note that this is a separate configuration from the individual SSC alarm relay
configurations which may be individually set per SSC module.
The default setting for the Fault alarm relay is Energized and is so for the purpose of wiring the Normally
Closed contact of the Fault alarm relay into a Fault Circuit that will indicate a fault if power is lost to the FM
or if the FM is unplugged from its slot.
1.2.3 Silenceable or Non-Silenceable
The terminology “to acknowledge an alarm” is synonymous with the terminology “to silence an alarm”. All
Alarms (Alarm1, Alarm 2, and Fault) can be programmed as Silenceable or Non-Silenceable. When an alarm
is programmed as Silenceable, the setting allows the alarm(s) to be silenced even during an alarm condition.