I have a trouble with ONVIF protocol.
I am making the camera controller on the ONVIF protocol using the C#. and I can find some ONVIF protocol doc. but that doc has no how to configure auxiliary command.
The one of the doc is https://www.onvif.org/wp-content/uploads/2017/07/ONVIF_PTZ_Client_Test_Specification_v1706.pdf.
The next one of the doc is https://www.onvif.org/specs/srv/ptz/ONVIF-PTZ-Service-Spec-v260.pdf.
And I have a sad article has a comment that "As result, from the VMS' GUI it is not possible to activate the Wiper, to run the Washing procedure, or to switch the camera to Night Mode.". https://support.videotec.com/hc/en-gb/articles/204773035-How-to-manage-Special-Functions-using-ONVIF
So, Really can not External program set the auxiliary command???
I'm not sure if this will help, but here's a piece of code using the ptz module of the ONVIF protocol...
https://www.codeproject.com/Tips/1192709/ONVIF-PTZ-Control-in-Csharp
You're supposed to be able to get a list of possible AUX command throught the GetNode function of the ptz ver20 .wsdl
https://www.onvif.org/onvif/ver20/ptz/wsdl/ptz.wsdl
You should then be able to use the SendAuxiliaryCommand form the same .wsdl
I hope this helps!