17
65-2619RK-CH4-4 M2 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 M2. During normal operation, this signal tracks
the gas concentration on the LCD.
There are several circumstances where the signal output will not track the display reading
but will behave as follows:
•
When the M2 is in its warm-up period, the signal output will be fixed at 3.5 mA (zero).
•
When the M2’s gas type is changed, the M2 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 M2 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 M2 returns to normal
operation.
•
If the M2’s input power decreases below 18.5 volts so that the M2 is in a low power
alarm, the signal output is fixed below 2.4 mA until the low power alarm is cleared.
•
If the M2 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.
Alarm Indications
NOTE:
The M2 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 22 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.
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