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65-2661RK-03-04 M2A Transmitter Operator’s Manual
4 - 20 mA Signal Output Operation
The output at the S terminal of the power/signal terminal strip is a 4 - 20 mA signal that
corresponds to the detection range of the M2A. During normal operation, this signal
tracks the gas concentration on the OLED display.
There are several circumstances where the signal output will not track the display reading
but will behave as follows:
•
When the M2A is in its warm-up period, the signal output will be fixed at 3.5 mA
(zero).
•
When the M2A’s gas type is changed, the M2A will enter Configuration Mode for you
to verify the parameter settings. When you exit Configuration Mode, the display will
indicate NEEDS CALIBRATION and will continue to indicate this until Calibration
Mode is entered and a calibration is performed. In this situation, the signal output will
be fixed at 3.5 mA from the time Gas Type Mode is entered until the M2A is calibrated
and returns to normal operation.
•
If you enter Calibration Mode, Configuration Mode, Gas Type Mode, or Modbus
Mode, the signal output will be fixed at 3.5 mA until the M2A returns to normal
operation.
•
If the M2A’s input power decreases below 18.5 volts so that the M2A is in a low power
alarm, the signal output is fixed below 2.4 mA until the low power alarm is cleared.
•
If the M2A goes into a fail condition, after a 30 second delay, the signal output is fixed
below 2.4 mA until the fail alarm is cleared.
During the 30 second delay, the signal output
follows the detector output. In the case of a downscale reading, the display and the signal
output continue to track the reading down to -99% of full scale (1.15 mA).
Alarm Indications
NOTE:
The M2A includes alarm on and alarm off delay settings for alarm 1 and alarm
2. The alarm indications described in this section operate according to the
factory set alarm settings. See Table 5 on page 24 for all the factory settings.
Table 4: Visual and Audible Alarm Indications
Condition
Cause
Visual Indication(s)
Alarm 1
1
Increasing gas reading at or above the
alarm 1 setpoint
• A1 LED is on
• Gas reading alternates
with ALARM-1 message
Alarm 2
1
Increasing gas reading at or above the
alarm 2 setpoint
• A2 LED is on
• Gas reading alternates
with ALARM-2 message
Fail
• Disconnected or misconnected
detector wiring
• Display reading at -10% of full
scale or lower
• Defective components
• F LED is on
• FAIL message replaces
gas reading
NOTE: There is a 30 second
delay on the fail condition.
