Problem with SSR control of router

[marzetti]

I'm hoping someone can give me an explanation/solution for my problem.
I have a gantry router running EMC2 with a CNC4PC C10 breakout board.
My router is controlled with a solid state relay. This setup works great except for one problem: if I turn the computer off without turning off the router power on my control box the router will start automatically. I know I could simply always remember to shut down the power first but I worry about an accidental shutdown of the computer.

Thanks,
Greg

[Al_The_Man]

Does EMC2 have a charge pump output you could use or a watchdog timer that could be set up as an emergency stop or in the E-stop string that detects PC failure or shut down?
This is usually the way it is done in industrial systems.
Al.

[marzetti]

I'll have to check on the charge pump/watchdog. I'm still trying to figure out the "why" of this situation, though. The relay turns on with a high signal so which should go low when the computer is off, yes? Just doesn't make sense to me.

[Al_The_Man]

Is the power supply for the CNC4PC still active?
Al.

[marzetti]

Yes, all the electronics in my control box run from a common 5v supply.

[Al_The_Man]

That could be the reason that if the CNC4PC is still live when the PC shuts down, and the SSR is triggered from the CNC4PC, it most likely faults out to the logic level required by the SSR to switch on.
Al.

[marzetti]

Thanks Al. I think I will contact Arturo at CNC4PC about this. He was very helpful when I set up my system. I'm definitely not an expert in electronics but I wonder if maybe a resistor could be installed to pull that output down?

[Al_The_Man]

I don't think that will be a suitable answer especially if the 5v for the BOB is still present.
If the reason is as mentioned so far, the absence of the PC signal sets the SSR to on state via the BOB supply.
Al.