Problem- parallel port interference?

[wvlaeminck]

Hi,
I have an EMC2 running on a 'relatively' recent computer (AMD athlon), using stepper 3-axis configuration.
I am constantly getting pulses on lpt port pins 2 & 3 (x-axis in my configuration), as long as EMC2 or EMC2 configurator motor test are not started.
If the system is in idle status (ubuntu started up, no programs active), the lpt is pulsing. If I move the mouse over the screen, the puses vary in speed.
Once I activate emc2 or emc2 motor test, the lpt gets stable and the pulses disappear.
I am worried that my router will be moving all the time, when I don't disable the drivers. Disabling the drivers is a solution, but it's dangerous, since forgetting to disable could lead to damage (pulses are not very fast, but very unpredictable).
I've tried this on 2 other computers, same result.
A friend of mine has an identical setup on another computer, and no interference at all.
Anyone know what's wrong? Is there a setting I've overlooked? (maybe in the bios?)

Thanks,
Wim

[Easydad]

are you running in axis?

[wvlaeminck]

yes, running axis is not a problem.
But the jitter occurs when I am out of axis, for example with the ubuntu desktop open and no other programs open.
From the moment I open axis and activate the cutting program, jitter is gone.

[Easydad]

It sounds like you don't have an interface board on the paraport to drives (gecko?). Look at cnc4pc.com their c-10 interface board. The gecko's have isolation inputs, so set-up with Arturo's boards is easy, he has pull-up resistors on the pins for clear true voltages. If you have a break-out board already, look for noise close to the communication wires. I hope you have signal wires with a metal sleeve and a drain wire to ground. If you have a Bob Campbell board--DUMP IT. The Campbell boards I had combined grounds from the table and computer, you will get lots of problems.
Hope this helps.

Easydad

[Big John T]

I second the cnc4pc BOB it is great.

John

[wvlaeminck]

Hi,
To make things more clear: under EMC2, when in operation mode, the system works fine. So moving axes is not problem, as long as EMC2 is open, or while the motors are under test in EMC2 configuration.
Only when I go out of EMC2, or if I close Test mode under the configuration, the uncontrolled pulsing on the parallel port appears.
As soon as I start up the computer, the movement begins. Only STOPS when I activate EMC2 and actually drive the motors.
I have good BOB with optocoupling; Portescap drivers with optocoupling. Again, driving the motors works without problem; only when I am not driving them using EMC2 or any other CNC software, my parallel port is living it's own life.
I have tried applying changes to the computer's BIOS, no luck until now.

If anyone knows what is happening, I would be gratefull.

[unterhaus]

sounds like the hardware discovery software is writing to the port.

[Easydad]

I second the software driving the para-port output. Due to your reluctance to list your configuration and the fact you keep repeating the same thing and asking for help; I don't know of anything else anybody can do for you.
Read the wiki on EMC2, change your para-port bios to whatever gives you the lowest noise. Load latest version of Ubuntu. Dedicate a desk-top computer to EMC2, not a lap-top (known issues w/para-ports). E-mail Jon Elson on EMC2 help blogs w/full details of your set-up. Purchase high quality grounded-cable, don't dual-boot, ect., ect.

Easydad

[unterhaus]

it really sounds like there is some problem with the way the parallel port works on that computer. Maybe an add-in parallel port card is a good idea.

The other thing is to get a BOB with a watchdog switch so that the router is disabled if the watchdog isn't getting a good pulsetrain. While this doesn't guarantee that the problem with your system isn't going to cause a problem, it does reduce the probability by a good amount.

is the parport module loading?

lsmod | grep parport

or

/sbin/lsmod | grep parport

should tell you

[wvlaeminck]

I will try reformatting my harddrive and go away from double boot, as it is the case now. Maybe then the system will get stable.
I will also try a cable with double ferrite cores, only I doubt that this is the solution.

Will keep you updated, thanks a lot for the help so far!!

Wim.

[wvlaeminck]

Last information update: I have been unable to solve the problem with this computer. As far as I have been able to find out, the problem is hardware related, as I could not trace it back to any malfunction of EMC2, Linux or my stepper driving hardware.
I have solved the problem by getting another computer. Everything worked well, no jitter anymore.
I don't have any idea why my first computer did show these strange pulses on it's parallel port. But it's not that important anymore.
The computer I use now is a HP E-PC 40, a really tiny machine perfectly fit for the job. It's not a speed monster, but it is driving my machine like I want it. And it doesn't take any space at all.

Thanks for the feedback I received, this topic can now be closed.

[garval82]

It happened to me also, testing a driver in a protoboard, what i found was that my parallel port ground (pin18-25) was open, just place a cable from your computer chasis to your system ground.