Vaisala GMP231 - Manual (Page 21)

Chapter 2 ___________________________________________________________ Product Overview
VAISALA ________________________________________________________________________ 19
Analog Output Overrange Behavior
Analog output of the GMP231 has a defined behavior when the values
measured by the probe are outside the scaled analog output range:
- Output is allowed to go 10% over the scaled range.
- Output is set to error state when measured value is more than 10%
outside the scaled range. See section Analog Output Error State on
page 84.
- Output resumes normal function when measured value returns to
within 10% of the selected range.
For example, consider a GMP231 with 0 ... 20 mA analog output, scaled
to 0 ... 10 %CO
2
.
- When measured CO
2
rises above 10 %CO
2
, the output rises above
20 mA.
- The output keeps rising until the measurement is 11 %CO
2
, at which
point the probe outputs 22 mA.
- If the CO
2
level rises above 11 %CO2, the output enters the error
state, which is 23 mA for the 0 ... 20 mA output.
NOTE This overrange and error state behavior is specific to the analog output,
and does not affect the readings provided by the digital outputs.
You can change the analog output overrange behavior using the AOVER
command. See section Set Analog Output Clipping and Error Limit on
page 46.