Author Topic: motors change direction using test programme but will only jog in one direction  (Read 1797 times)

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Offline plumbdoguk

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my motors will go both ways when using the roadrunner test programme but if I try to manually jog they will only turn in one direction using the keyboard or mouse after this initial discovery i have added a manual wheel and this also only does the same I'm just in the initial stages of setting up the machine i have built and am new to mach3 am i missing something really obvious in the configuration i have checked and re checked all the wiring to the drivers and the ports and pins but cannot understand why the test programme runs perfectly but the manual jog does not if anyone has come across this before or has an idea as to why this is happening i would be gratefull for any feedback

Offline Tweakie.CNC

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This problem can occur if the LPT parallel port (or motion controller) output is to the newer 3.3Volt TTL standard and the motor drivers are expecting a signal that is to the older 5Volt TTL standard.

Measure the voltage on an axis Direction pin and if the maximum voltage (measured whilst jogging in either direction) is 3.3Volts then that could be the issue. If you are using the computer's LPT parallel port then consider fitting a 5Volt PCI parallel port card but check these details first:  http://www.machsupport.com/forum/index.php/topic,34848.0.html

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline damianp

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Help! I'm experiencing almost these same symptoms, but only AFTER moving my set up from the basement to the garage. It had been working perfectly before the move. Triple checked all the wiring. Good. System is an older XP desktop with onboard LPT which does show 5 volts output. Additional symptoms are... for example - press Z+ the stepper motor runs fine BUT only maybe up or maybe down. It changes whether it goes up or down with each button press. I'm completely flummoxed.

Offline Tweakie.CNC

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From what you describe I would suggest that you check your wiring connections for a missing Ground (or possibly Earth) connection between your equipment. Also check your LPT cable pin for pin and all other cables for continuity. If you have changed or replaced anything during the move then that would be the first place to start looking.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.