TB6560 controller Runs spindle on power up When Mach3 plunges spindle stops

[JAZZCNC]

All seems OK BUT when I power up the TB6560 controller the spindle starts immediately even if PC is off line.

It sounds like it's wired wrong at the board because it's doing it while PC is off so Mach3 isn't in control. Chances are the board use's a relay and it's wired thru the wrong contact. It should be wired thru NO (normally open) contact so then Mach3 sends a signal to the relay to change switch state and closes the contact starting the spindle. This has been wired wrong way round using the NC (normally closed) so power is allowed to pass thru to the spindle soon as you turn on the TB6560.!!! . . . . . .!!!VERY UNSAFE!!! . . . . Mach3 then turns it off by changing the output pin state when it see's M3/M5 command in g-code.

So swap the relay contact to NO and you should be good to go. You won't need to change the pin active state in outputs. What Silyavski suggested would work but it's not correct as the spindle shouldn't start when board is powered. Again VERY DANGEROUS and I would look at how you have wired regards safety and E-stop etc.