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Chapter 4: Operation
65-2670XL-XX-07 M2A-XL Transmitter
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-XL. 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-XL is in its warm-up period, the signal output will be fixed at 3.5 mA
(zero).
• When the M2A-XL’s gas type is changed, the M2A-XL 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-XL 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-XL returns to normal operation.
• If the M2A-XL’s input power decreases below 9.5 volts so that the M2A-XL 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-XL 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).
