I use PJlink over LAN.
It is not that complicated.
- connect projector lan to the same network as the node red server.
- assign a ip to both. note down the IP adres of the projector. Also, and it is best to refer to the user manual, find projector's default login or set it in the projection menu.
I use panasonis, most times the default is user1 login and panasonic as password
- in node-red create a pjlink node
- in the node settings fill in the ip adress, default port is ok, fil it in! it is sort of greyed out.
- name is the loginname, that is a bit confusing, since loginnames of multiple porjectors are all the same!
- password is password.
If you send a message topic ON or on to the projector, it will turn on.
If you send OFF or off the projector will turn off.
some projectors do need to set an password since blank does not work. especially more older projectors (PJ link rev 1.0)
it is also possible to torn on or off projectors through rs232. but this does not work with the node red contrib.
My guess for that is to start here: