Analog output overrange example - GMP251

GMP251 User Guide

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Consider a probe with 0 ... 5 V output, scaled to 0 ... 200 000 ppm (= 0 ... 20 %) CO2.
  • When the measured CO2 rises above 20 %, the output rises above 5 V.
  • The output keeps rising until the measurement is 21 %CO2, at which point the probe outputs 5.25 V.
  • If the CO2 level rises above 21 %CO2, the output still remains at 5.25 V.
  • If the CO2 level rises above 22 %CO2, the output enters the error state, which is 0 V for the 0 ... 5 V output.
Figure 1. Example of analog output overrange behavior

This example uses output scaled to 0 ... 5 V and 0 ... 200000 ppm, 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.

This overrange and error behavior is specific to the analog output, and does not affect the readings of the digital outputs.

You can change the analog output overrange behavior using the aover command.