Model 2180A
16
• The status indicators provide the user with an indication of the current mode of
operation: HIGH (high alarm), LOW (low alarm), FAULT, SETUP (setup and
setup check modes), and CAL (calibration or calibration check modes).
• Mode button provides the user access to the Calibration, Calibration Check,
Setup and Setup Check modes. The Mode button is accessed using a small
screwdriver in the front of the unit.
• The Reset button allows the user to reset latched alarms.
3.2 Initial Application of Power
Before applying power for the first time, double-check all the wiring components. Insure
that the sensor is correctly installed.
The system has a time delay feature. The High and Low alarm circuits are disabled for
approximately 45 seconds after power is applied. This feature prevents false alarms while
the sensor circuits are stabilizing.
At the initial application of power, the unit will enter a 45-second start-up mode. During
this time, the display will read “SU”. The unit will then enter operational mode and the
current gas concentration of the sensor will display. If a channel fault occurs, the FAULT
LED will flash, the fault relay will become active and the unit will display the appropriate
error code. This fault indication is independent of the abovementioned time delay feature.
3.3 Resetting Latched Alarms
The user may select a “latching” or “non-latching” alarm output for High and/or Low. If an
alarm output activates and the condition that caused that activation is no longer present,
a non-latching alarm output resets automatically. A latched alarm output needs to be
reset manually.
Resetting latched alarm outputs is done with the Reset button located on the master
board. Pressing the Reset button resets any latched conditions that are no longer valid.
EXAMPLE: The sensor detects a gas concentration in excess of an alarm set point. The
associated alarm outputs activate. After a few moments, the gas
concentration drops below the alarm set point. If the alarm outputs are
latched, the operator can press the Reset button and the latched alarm
outputs return to the normal (safe) state.
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