Need Help!- Unstable -- Mach 3 random output pulse

[cjchands]

I don't know weather it is the noise or something else, but there is a problem now when I connect Parallel port to the breakout board and MACH 3 is on.
X-Axis motor would rotate tiny bit at a time.
Sometimes Y-Axis and Z-axis as well.
Sometimes LIMIT detected when it doesn't hit any limit at al.

All these weird movement is HAPPENED while there is NO command sending out from MACH3, but I detect HIGH output when it shouldn't be there!. It moved tiny bit...

It does seem the problem happen randomly.
When disconnect Parallel port, there is ZERO output which to be expected.

I am using shield cable for signals, separate from power line, and can't seem to detect what the problem is? COMPUTER? I changed 2 different PC and it seem to act the same way when connect Parallel port to Machine..

If it is NOISE, then not exactly sure where it is came from?

Any advice is appreciated.
Jeff.

[carvemylog]

Not sure about the random movements, but there's a couple things you can do about the random limit switch hits. Under the general config menu you can change the debounce amount up. I'm running 10,000 on the debounce.

When I first started running my machine it was almost unusable, it would hit false limits about every 10 seconds. Adjusting the debounce helped, but what really helped was putting .022 uf capacitors between the limit switch signals and gournd on my BOB.

As far as the random movements, it sounds like somehow noise is getting to your stepper drivers. I would check all the grounds, make sure the PC and power supplies are all on the same circuit. If still having prob;ems, maybe try a different BOB