PWM output on CNC BOB

[jolyonjenkins]

I have another problem. When the machine is on, but the computer is off, pin 17 (the relay) goes high and so the relay switches on. Do I need to pull it low?

[dazp1976]

I have another problem. When the machine is on, but the computer is off, pin 17 (the relay) goes high and so the relay switches on. Do I need to pull it low?

If you pull it low the relay will just work backwards.

You should always have Mach pc in control BEFORE you turn on the controllers themselves.
When finished. Turn off controllers first, then shut Mach pc down.

I used to get a relay flicker when powering on the pc, that was when I used usb for my 5v input.
I now use a seperate supply into the 5v & gnd terminals on the bottom row of the board for isolation.