Analog Output - GMP251

GMP251 User Guide

Document code
M211799EN
Revision
G
Language
English (United States)
Product
GMP251
Document type
User guide
Table 1. Amode Command
Syntax Description
amode [channel]<cr> Show currently set analog output limits and error level.

channel = Analog output channel

  • 1 = voltage output (V)
  • 2 = current output (mA)
amode [channel lo_value hi_value error_value]<cr> Set new analog output limits and error output value.

channel = Analog output channel

  • 1 = voltage output (V)
  • 2 = current output (mA)

lo_value = Low limit of the channel.

hi_value = High limit of the channel.

error_value = Error value of the channel.

When setting the error output voltage, note that the probe's maximum voltage output is 10.325 V.
Example (show current configuration):
pass 1300
amode 1
Aout 1 range (V) : 0.00 ... 10.00 (error : 0.00)
amode 2
Aout 2 range (mA) : 4.00 ... 20.00 (error : 2.00)
Example (set channel 1 to 0 … 5 V, and error output to 0.0 V; set channel 2 to 0 ... 20 mA, and error output to 23 mA):
amode 1 0 5 0.0
Aout 1 range (V) : 0.00 ... 5.00 (error : 0.00)
amode 2 0 20 23
Aout 2 range (mA) : 0.00 ... 20.00 (error : 23.00)
Table 2. Aover Command
Syntax Description
aover [channel<cr> Show the behavior of the analog output when the measured value is outside the scaled output range.

channel = Analog output channel

  • 1 = voltage output (V)
  • 2 = current output (mA)
aover [channel clipping error_ limit]<cr> Set the behavior of the analog output when the measured value is outside the scaled output range.

channel = Analog output channel

  • 1 = voltage output (V)
  • 2 = current output (mA)

clipping = Output margin (%) at which the output is clipped.

error_limit = Measurement value margin (%) at which the output of the channel goes into the error state. The current or voltage output of the error state is defined using the amode command, see Table 1 on the previous page.

Example (view currently set analog output overrange behavior on channel 1):
pass 1300
aover 1
Aout 1 clipping :5.00 %
Aout 1 error limit :10.00 %

Example (for channel 1):

  1. View currently set analog output scaling (asel command), limits and error level (amode command), and overrange behavior (aover command):
    pass 1300
    asel 1
    Aout 1 quantity : CO2(0 ... 200000)
    amode 1
    Aout 1 range (V) : 0.00 ... 5.00 (error : 0.00)
    aover 1
    Aout 1 clipping :1.00 %
    Aout 1 error limit :5.00 %
  2. Set analog output overrange clipping to 5 % and error limit to 10 %:
    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 5.00 %, meaning the voltage output is allowed to vary between 0 ... 5.25 V. The analog channel will output the measurement for 0 ... 210 000 ppm, but range 0 ... 5 V remains scaled to 0 ... 200 000 ppm.
  • Error limit is 10 %, which means the output will show the error state (0 V) when the measured CO2 concentration is 10 % outside the scaled output range. With the settings above, this will happen if the measured CO2 concentration is outside range 0 ... 220 000 ppm.
  • The voltage output will never be above 5.25 V because of clipping: the voltage output is clipped when the output reaches 5.25 V, and if the measured CO2 concentration keeps rising above 220 000 ppm, the output jumps directly to the error state 0 V.
Figure 1. Example of Analog Output Overrange Behavior

The example shown above uses output scaled to 0 ... 5 V and 0 ... 200 000 ppm, has error level set to 0 V, clipping set to 5 % overrange, and error limit set to 10 % overrange. CO2 concentrations (ppm) are indicated for the clipping point and error limit point.

Table 3. Asel Command
Syntax Description
asel [channel]<cr> Show the parameter and scaling of the analog output in ppm.

channel = Analog output channel

  • 1 = voltage output (V)
  • 2 = current output (mA)
asel [channel] [parameter lowlimit highlimit]<cr> Set the parameter and scaling of the analog output.

channel = Analog output channel

parameter = Parameter that is output on analog channel. The only parameter available is CO2 (in ppm).

lowlimit = Lower limit of channel scaling in ppm. Minimum value is -1000000 ppm (= - 100 %).

highlimit = High limit of channel scaling in ppm. Maximum value is 1000000 ppm (= 100 %).

Example (for channel 1, show the currently set analog output parameter and scaling):
pass 1300
asel 1
Aout 1 quantity : CO2(0 ... 200000 ppm)
Example (for channel 1, set scaling to 0 ... 10 % (= 100 000 ppm)):
pass 1300
asel 1 co2 0 100000
Aout 1 quantity : CO2(0 ... 100000 ppm)