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Author Topic: Motor "Sometimes" goes in Wrong Direction while Tuning  (Read 8828 times)

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Offline Tweakie.CNC

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #10 on: March 18, 2009, 01:30:20 PM »
Hi Jamie,

No other suggestions, sorry.

Incidentally do the motors have sufficient torque ?. (can you stop them with little force when they are rotating).

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #11 on: March 18, 2009, 01:48:44 PM »
no they seem pretty powerful and when i turn up the velocity and accelleration they take off fast and smoothly and go rapidly
it is just very frustrating to see them go the right way 3-4 times then the 5th time go the wrong way.

Thanks again for putting your mind towards my problem.

Offline Hood

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #12 on: March 18, 2009, 03:10:00 PM »
Put a Voltmeter between the 0V and Dir pin on your BOB and jog back and forth to see if it goes 5v to 0V when you jog one way and 0v to 5V when you jog the other. It may well be that you only have 3.3v from your port which will be your problem as they are often not good enough to drive the drivers. To solve that problem you could get a BOB which is powered, most of them can accept the lower 3.3v signals and will output 5v. The ones I like are the PMDX 122.
Hood
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #13 on: March 18, 2009, 03:45:33 PM »
when you say 0 volt you are saying put one contact on the ground and the other on the direction pin at the break out board or on the driver? to check this?

ok the 5 volts that it should be getting is from the computers power supply on my system.  is that adequate? I guess i will find out for sure when I get home tonight to check

thank you all for your your time and input

Jamie

Offline Hood

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #14 on: March 18, 2009, 04:05:24 PM »
Yes thats correct, its commonly called Gnd but really its 0V, doesnt matter whether its the BOB or the Drive as they are one in the same with a non powered BOB, so whichever gives you easiest access.
The 5v it is getting is from the parallel port which ultimitely is coming from your computers PSU and yes it will be adequate, however modern design of parallel ports often has them powered by 3.3v rather than 5v which causes problems with the drives not picking signals up properly on occasions. Using a powered BOB will eleviate this problem as the BOB will be happy with the 3.3v signals from the port but it will put out 5V so that the drives are happy. As was mentioned optically isolated BOBs are not always a good thing when it comes to drives that have optos already in them, so best to make sure any powered BOB you may get doesnt have optically isolated outputs for Step/Dir pins.

Hood
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #15 on: March 18, 2009, 10:46:54 PM »
Hood you were correct i am only getting 3.3 volts to the BOB on pins 1-9 and when i change directions it drops to .51 volts

but on pins 11-15 I am getting 5 volts but the voltage does not drop at all no matter what direction i move the table.  so I moved my direction wires to pins 10 and 11 just to try it and it still goes whatever direction it pleases.

So do you still feel i need a different breakout board?

Thanks again for your time

Jamie

Offline Hood

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #16 on: March 19, 2009, 03:55:22 AM »
Port 1,  Pins 10 to 13 and  15 are Inputs so you cant put motors on them.
 Cant say for definite that it will cure your problem but certainly would suspect it will. A cheaper option for you may be to get a PCI parallel port and use that as they tend to be 5v, but again some are some are not.
Hood
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #17 on: March 20, 2009, 09:30:04 AM »
i purchased a powered pci card so after getting my spiffy new thing and installing it

it proceeded to do the same thing it had been doing 3/5 or 4/5 it would do what i asked it to then it would do whatever it wanted to do.

after much head scratching I thought despite what I had been reassured I really think my motors are wired wrong.  So i got out my multimeter and sure enough they were out of phase for their continuity.  So i rewired them to be in phase and voila they work perfect.

thank you all for taking the time to help me

Jamie

Offline Hood

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Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #18 on: March 20, 2009, 10:01:31 AM »
Thats great news :)

Hood
Re: Motor "Sometimes" goes in Wrong Direction while Tuning
« Reply #19 on: March 20, 2009, 10:03:59 AM »
I thougth so and i even made some cool circles in styrofoam and some rectangular pockets as well.  My wife wasn't nearly as impressed as I was with my projects ;-)