Don’t know if this is even possible, but I’ll ask anyway. For those of us that use DLP projectors, we want to turn them off after a print. Sure, some projectors have a serial interface, but if we haven’t gotten that working, we must be there to turn it off manually after the print to save bulb life. Almost all projectors have an automatic shutdown feature if the video input shuts off. If there were a command we could add to turn off HDMI after completion of a print, then our projectors would automatically shutdown.
Starting a projector manually is not a big deal, since you have to be at your printer to make sure it is ready to print anyway.