Detcon 10C - Manual (Page 6)

Model 10C
1.1 Display Function
The main purpose of the 10C Controller’s 4-character display is to show the gas concentration reading at all
times. The reading is given in numeric form and with the desired units, as converted from the current input
signal of the attached gas sensor. Upon operation of the pushbuttons, the display also allows viewing gas type
and units very simply, and with further manipulation allows viewing of any configurable setting.
1.2 Alarm Functions
The alarm configuration, programmed into the controller, determines how the 10C Controller responds to the
4-20mA current-loop analog input. In response to the analog input relative to alarm configuration, the
Controller outputs to its relays and panel LEDs. Alarm configurations for the alarm output relays and LEDs
can be programmed as latching or non-latching, ascending or descending, energized or de-energized, and
silenceable or non-silenceable operation. Any combination of these settings can be programmed to provide
setups for almost any contingency. Some planning may be needed to determine the best configuration for the
application.
1.2.1 Latching or Non-latching Relays
All alarms, 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 analog input “clears”.
NOTE: The term “Clear” refers to when the alarm condition of the sensor signal returns to
normal, which means that the input current changes to the non-alarm side of the Set-Point
threshold.
If an alarm is programmed as Non-latching, the alarm will not remain activated if the analog input clears.
There is a reset pushbutton on the 10C front panel and there is also a signal input to the 10C controller via the
backplane where an external switch can be connected. When the “Reset” pushbutton on the front panel or the
external switch is momentarily activated, the 10C accepts the signal as an alarm reset function. If resettable
alarms are latched, and in response to the front panel reset switch, the 10C front panel display will scroll the
text: “Reset Alarms?” In response to this query, the “ENT” pushbutton should be pressed to acknowledge the
reset. In response to an front panel reset button acknowledgement , the front panel display scrolls the text:
“Reset DONE”.
The external reset does not have an acknowledge feature and when the 10C Controller senses that the external
reset signal is momentarily activated, the 10C scrolls a text message on its front panel display: “Ext Alm Rst”.
1.2.2 Energized or De-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, however, a relay can be programmed as Energized
to provide application specific features. For De-energized relays, the coil will energize in an alarm state. For
Energized relays, the coil is normally Energized and will de-energize in an alarm state. It should be noted that
with a normally Energized relay the N.O. (Normally Open) contact and the COM (Common) contact are
CLOSED, and the N.C. (Normally Closed) contact and the COM contact are OPEN, while in the non-alarm
state.
10C Control Module Instruction Manual Rev.0.B Page 2 of 25