First, please update to RRF 3.2.2 by uploading this zip file to the system tab in DWC.
https://github.com/Duet3D/RepRapFirmware/releases/download/3.2.2/Duet2and3Firmware-3.2.2.zip
@wittj2 said in Berd air pump to E1 output:
M950 H2 C"nil"
In RRF3 beyond 3.0 you no longer need to "free up" a pin before you can use it. They are free by default and must be defined to be used. So no more nil unless you want to free up a pin that you've already defined once for reuse as something new.
After that I think your gcode should work ok.