Frage Dust extraction - how to start and stop ?

Hi,

I've made my own homemade dust extraction system for my Steppi 840. It works OK.

But now, I want to stop it when the job is done, or say, when the spindle stops, because I want to start a new job at the end of the working day, leave it running overnight, and have it ready in the morning.
But then of course, I do not want the vacuum-cleaner running all night.

Can anybody point me in the good direction for this ? I know I have to play with the GCode, and I know I can attach external relais but I do not know any details, and do not find anything about this on the net.

Thanks.
Gerry.

I bought this set of controlled sockets www.amazon.com/gp/product/B00DQELHBS/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 from amazon. I set the remote so that switch 1 does the machine and a light, switch 2 does the milling head, switch three does the vacuum.

I think it's a real bad idea to let the machine run alone. See here, or here what can happen. Probably no insurance will pay if the machine sets your house on fire while you are sleeping.