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IndustryArena Forum > CNC Electronics > CNC Machine Related Electronics > Need help with manual pulse generator
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  1. #1
    Join Date
    Sep 2006
    Posts
    300

    Need help with manual pulse generator

    I have a plug-in pendant:

    CNC4PC

    This is the board that connects it to the2nd parallel port:

    CNC4PC

    The problem is, it will only jog in one direction.

    When it is turned clockwise, the machine will go in the -neg direction.

    When turned CCW, nothing??

    I have traced down the wire and they appear to be on the correct pins.

    How do you test an MPG?

    If it pulses clockwise, shouldn't CCW be ok also?

    Does it require A & B both to pulse?


    Thanks for the help,

    JAckal:wave:
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  2. #2
    Join Date
    Jan 2006
    Posts
    2985
    A and B are required to determine direction of rotation. If A is logic high when B goes high, it is going one direction. When A is logic low when B goes high, it is going the other direction. You need both connected. To troubleshoot, you could swap the A and B wires where they connect to the board. If its still clockwise only, your software or board probably has an issue. If it will only go CCW, then the encoder probably has a problem.

    Matt

  3. #3
    Join Date
    Dec 2003
    Posts
    24216
    The symptom is what you would expect with one channel missing, most MPG's use a 100p/rev quadrature encoder as a source, and has been said, you need both A & B.
    to count up and down.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
    Join Date
    Sep 2006
    Posts
    300
    Thanks Keebler & Al.


    I reversed the wires A&B on the back of the Hedds Encoder (handwheel).

    It still only jogs in the -neg direction, but with a CCW rotation of handwheel.

    JAckal:cheers:
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  5. #5
    Join Date
    Dec 2003
    Posts
    24216
    You can use a meter from common to each A & B output and if you turn VERY slowly while monitoring the A pulse, as soon as it goes high, check the B it should always be low in one direction and always high in the opposite dir, whenever the A transitions to +5v.
    Easier with a 'scope though.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  6. #6
    Join Date
    Sep 2006
    Posts
    300
    Al,

    I tried checking itwith a meter. When the (A) side is at 4.87 volts+, the (B) is at 0.08 volts or 2.87v max.

    It was real tricky to hold the (A) at the certain click where it would stay at high side.

    Something that I did notice in the Mach diagnostics page:

    Click image for larger version. 

Name:	Mach diagnostic   leds.JPG 
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ID:	144659

    The (2) LEDs that are circled, were flickering.

    It was like a Morse-code or something. They would go back and forth making long or short flashes while the hand-wheel was being turned.

    They did this in both dir. of the hand-wheel.


    Thanks,

    JAckal:wave:
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  7. #7
    Join Date
    Dec 2003
    Posts
    24216
    They should both transition from 0v to +5v, or close, these are not open collector outputs by any chance?
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  8. #8
    Join Date
    Sep 2006
    Posts
    300
    Al,

    I'm not sure. I don't really know enough to say either way.

    Here is the technical data for the encoder in the pendant:

    Click image for larger version. 

Name:	MPG  specs.jpg 
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ID:	144669


    Hope that helps.

    If not, maybe Arturo at CNC4PC can give me more info.

    Thanks,

    Jack
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  9. #9
    Join Date
    Jan 2006
    Posts
    2985
    This is what the encoder should output: http://upload.wikimedia.org/wikipedi...re_Diagram.svg The flickering LED's should also blink in this pattern. If they are not, the voltage level you are seeing may not be sufficient. It appears that your encoder has a line driver output rather than an open collector output. That is good for you. You could also try to disconnect the A and B wires and measure the voltages without anything connected to them. You could further emulate the encoder action by jumpering the B signal to either the common or the 5v encoder supply and pulsing the A input by rapidly connecting and disconnecting it from the 5v supply. It should make the axis move one direction when B is held low and the other when B is held high.

    Matt

  10. #10
    Join Date
    Sep 2006
    Posts
    300
    Keebler,

    I am getting pretty much the same pattern in clockwise to CCW direction.

    Cw is:

    left
    left
    left then >right on same click
    right
    right
    both
    right right
    none

    Ccw is the same pattern, with a couple of differences.

    I am going to reload my brains in Mach3, for about the 5th or 6th time.

    All of the sites keep saying to do that as many times as it takes.

    I'll keep everyone posted,

    Thanks for everyone's help,

    JAckal:wave:
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  11. #11
    Join Date
    Jan 2006
    Posts
    2985
    I realize now my link was not good. This is what I meant: File:Quadrature Diagram.svg - Wikipedia, the free encyclopedia

    So your pattern should be:

    right
    both
    left
    none
    right
    both
    left
    none

    and the other way:

    left
    both
    right
    none
    left
    both
    right
    none

  12. #12
    Join Date
    Sep 2006
    Posts
    300
    After jumping the wires manually ( momentary short pulses) it still only works in one direction. (With "B" at both neg- and at 5+pos)

    I'll check the LED pattern again, compared to the sample you gave me.

    Does the 5 volts have to be exactly 5?

    The voltage reading was 4.82 to 4.89.

    Does the parallel port need to be EPP or SPP?

    Mach was communicating perfectly through this parallel port.

    Could it be the c-22 interface board is bad?

    Next, I will connect the MPG directly to the parallel-port and get 5 volts to it.

    Any other ideas are welcome.

    Thanks a lot,

    Jack
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

  13. #13
    Join Date
    Dec 2003
    Posts
    24216
    The voltage looks fine.
    If you have a PC that runs DOS you could use this software to test them, I have input directly into the PP without the buffers shown with no problem.
    DRO SOFTWARE
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  14. #14
    Join Date
    Sep 2006
    Posts
    300
    Thanks for all of the help, guys.

    I have it working. The pattern from the Wiki file is exactly how the Leds pulsed.

    The problem is either the "Mach Brains or the C-22 card"

    The pendant cable checks continuity on each wire, from pendant to db 25 connector.

    I took an old printer cable and spliced in to it for the A & B connection.

    Then ran wires directly from the USB connector 5+volt supply plug to the Hedds encoder.

    After configuring Mach " Port & pins", it will jog either direction on any axis.


    It's no bother to go to the keyboard to change axis. The MPG with a long cord, and an mobile E-stop is all I wanted anyway.

    Maybe later I'll set up some hot key buttons on the pendant to change axis, etc.

    Here is a couple of quick phone pics of my hillbilly hook-up:

    Click image for larger version. 

Name:	Port cable MPG.JPG 
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Size:	37.2 KB 
ID:	144780

    Click image for larger version. 

Name:	Port cable MPG 2.JPG 
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Size:	46.9 KB 
ID:	144781



    Thanks for all of the help,

    JAckal:wave:
    Everything is bio-degradable, if you run over it enough times with the lawnmower.

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