Having problems with stepper enable driven relay enabled on linux boot

I am using a Sainsmart 5 axis breakout board (the one without pwm) to drive 5 axes on a knee mill. I am trying to use a relay to power up the stepper driver power supply on the enable pin. It seems to work ok when linuxCNC is running but when I start the machine the enable pin goes high. I tried using a 10k pulldown resistor on the relay but it had no effect, I think it is not simply floating.

Is there some way to set the parallel port pin value on startup or some other way to drive the relay besides the enable pin? I often leave linuxCNC running and power down the steppers so I can resume what I was working on later without having to rehome. I intend to use the onboard relay to drive the spindle.

 
 

Tommy, thanks for the response.

I am using 3 PCIE to parallel port cards (SD-PEX10005). One for mill, one for lathe and one for MPG pendant. Is it possible the breakout board is causing this and not the lpt card?

I moved over to one of the 5 axis breakout boards with PWM so I can convert spindle to VFD and it behaves the same as the sainsmart bob as far as enable high. I have some spare pins on the pendant db25, but I haven't had a chance to test them isolated from board connection. I spent the day installing the refactored tower in the shop.


I have the relay on the AC input to the stepper driver PSU.