Configuring analog output - GMP231

Show the parameter and scaling of the analog output in ppm.

channel = Analog output channel, only 1 can be selected.

Set the parameter and scaling of the analog output.

• parameter = Parameter that is output on analog channel. Only parameter available is CO2.
• lowlimit = Lower limit of channel scaling in ppm.
• highlimit = High limit of channel scaling in ppm.

Example (change channel scaling to 0 … 5 %):

pass 1300
asel 1 co2 0 50000
Aout 1 quantity     : CO2(0 ... 50000)

Show currently set analog output limits and error level.

channel = Analog output channel, only 1 can be selected.

• lo_value = Low limit of the channel.
• hi_value = High limit of the channel.
• error_value = Error value of the channel.

Example (show current configuration):

pass 1300
amode 1
Aout 1 range (mA)    :4.00 ... 20.00 (error :21.00)

Example (set channel to 4 … 20 mA, and error level to 3.6 mA):

pass 1300
amode 1 4 20 3.6
Aout 1 range (mA)    :4.00 ... 20.00 (error :3.60)

Show the behavior of the analog output when the measured value is outside the scaled output range.

channel = Analog output channel, only 1 can be selected.

Set the behavior of the analog output when the measured value is outside the scaled output range.

• clip% = Output margin (%) at which the output is clipped.
• valid% = Output margin (%) at which the output of the channel goes into the error state. The error state is defined using the AMODE command.

For example, first check the analog output settings using ASEL, AMODE, and AOVER commands:

pass 1300
asel 1
Aout 1 quantity     : CO2(0 ... 50000)

amode 1
Aout 1 range (mA)    :0.00 ... 20.00 (error : 23)

aover 1
Aout 1 clipping     :10.00 %
Aout 1 error limit  :10.00 %

Now give the following AOVER command:

aover 1 5 10
Aout 1 clipping     : 5.00 %
Aout 1 error limit  :10.00 %

The analog output now behaves like this:

• Clipping is now set to 5 %, meaning the output is allowed to vary between 0 ... 21 mA. The analog channel will output the measurement for 0 ... 52500 ppm, but range 0 ... 20 mA remains scaled to 0 ... 50000 ppm.
• Error limit is 10 %, which means the output will show the error state (23 mA) when the measured value is 10 % outside the scaled output range. With the settings above, this will happen if the measured CO₂ concentration is outside range 0 ... 55000 ppm.
• The output will never actually be between 21 mA and 23 mA because of clipping.

Test the operation of the analog output by forcing the output to a given value.

• channel = Analog output channel, only 1 can be selected.
• level = Level for analog output channel in mA.

You can then measure the output with a calibrated multimeter. After testing the output, use the ATEST command again to exit the test mode.

Example (enable analog output test mode, set level to 20 mA):

pass 1300
atest 1 20
Aout 1 (mA)    :20.000

Example (disabling analog output test mode, resuming normal output):

atest 1
Aout 1 test mode disabled.