EMC2 pulses parport on startup...

Hello all,

I've just upgraded to EMC2-2.4.3 after quite a long while running I don't even remember what version...one of the BDI installs. At any rate, I have a Dell Optiplex GX240 connected to PMDX-120 multifunction parallel port board.

When I start up EMC2, I find that some of the higher-numbered output pins (14 and 16) get a brief pulse. On this particular output board these pins drive relays which I would like to use to control the spindle (a router) through software. The problem is that if the relays are powered when I start EMC, the router spins up a little bit. Not quite what I want to have happen! Of course, I could just keep the router's ON/OFF switch off until after I start EMC, but it would be nice to not have to remember to do this. I am going to have to think of a way to lockout the router for tool changes anyway, but I thought I'd shoot this past everyone and see what happens.

thanks,
Pat

use the amplifier enable or is-on hal signal , to drive a relay so closing the spindle circuit only when Linuxcnc is switched on from the Axis screen etc .

Thanks for the reply.

I'm not sure if I understand what you mean.

Are you suggesting that I use a separate, offboard relay driven by a hal signal, rather than the relay that's already on my interface? I'd still have to drive the external relay via one of the parport pins, though, so if they're getting tweaked when I start EMC I think I'd still have the issue. Please elaborate!

tnx,
Pat

This is why fancier parallel port breakout boards include a charge pump, so no matter what BIOS/OS port probing does, the outputs can not turn on until the proper signal is received.

A charge pump also acts as a watchdog so if the computer crashes the outputs turn off in milliseconds

I always felt that the simplest solution is to always power up your equipment in the correct order as John pointed out.
On my router set up I have a row of lighted switches 1 for the computer, 1 for the stepper drivers, 1 for the router, etc.
I never power up the drivers or routers until LinxCNC is in control.
Of course a charge pump could give an additional layer of safety especially it more than one person is to use the machine.
By the way this is not a LinCNC thing you may find similar results on other systems.

I also make sure the switch on the router itself is also off anytime I need to work on it, change bits or make adjustment near it.

Rick G

Rick G wrote:

I always felt that the simplest solution is to always power up your equipment in the correct order as John pointed out.

Not only the simplest solution, it is the method used by every machine tool manufacturer. Both NPFA-79 and the equivalent IEC codes require manual enabling of all motive devices. This is always done after the computer goes thru it's self test. The machine enable circuit is inactive until the computer issues a ready signal. The ready signal goes to a safety relay, never directly to the enable pins.

By the way this is not a LinCNC thing you may find similar results on other systems.
Rick G

The early Galil controllers would send the motors running if you didn't disable the amps during power down. They also made a noticeable jerk if the amps were enabled when the computer was turned on.

Doug