EMS 1304 Installation And Operation Manual page 30

Service module
The service module is used to pass signals to and from the transceiver and control unit, display opacity via digital
meter, initiate maintenance zero and span cycles and insertion of external current meter in the transceiver to
control unit 4-20mA loop.
OPACITY / T2 - This switch selects the display of the stack digital meter. In the Opacity mode the digital displays
% Opacity from the control unit. In the T 2 mode it is the signal out of the transceiver in % Transmittance 2 .
- This switch controls the zero mirror solenoid. In the operate position the mirror is not in the
OPERATE / ZERO
measuring path and is considered normal operation. When the mirror solenoid is energized the mirror is placed in
the measurement path and is considered a maintenance condition, i.e. signal is not representative of the stack
smoke. The control unit will indicate a Fault.
 Energizing and observe the digital meter to test the systems response to zero % opacity.
 Energize in conjunction with the span filter to observe the up scale span % opacity calibration
point.
OPERATE / SPAN - This switch controls the span filter solenoid. In the operate position the span filter is not in
the measuring path and is considered normal operation. When the span filter solenoid is energized the span filter
is placed in the measurement path and is considered a maintenance condition, i.e., signal is not representative of
the stack smoke. The control unit will indicate a Fault.
 Energize in conjunction with the zero mirror to observe the up scale span calibration point.
NORMAL / TEST - This switch controls the EXTERNAL mA METER connections. In the normal mode the
terminals are shorted. In the test mode the terminals are open and the current loop from the transceiver is
interrupted allowing the use of an external current meter to be placed in series with the transceiver current output.
When this is in the test mode position it is considered a maintenance condition and fault condition. If no current
meter is in the test jacks the loop current the control unit will indicate full scale and the control unit will indicate a
Fault.
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