Step signal not working

I am using Mach 3, I have everything set up the way I want just to get things going. I am using CNC4PC C11G and some PoStep25 drivers at 24v.

My problem is I can get the enable, and Dir pin to work correctly but not the step pin. the light for that pin wont light up like the others on the bob. I have measured the voltage and with no activity it is at 0.0v and when I travel or jog it gets up to .04v and THATS IT! (others work at 0-5v no problem) Am I missing something?

The steppers move freely with no power and lock up with power applied. Dir pin voltage changes when I change direction. I went to Motor tuning and played with the pulse width 0-5 but no change. I have use a Multimeter to check the bob for these voltages but whenever I unplug the electronics and test the cable directly the voltage never changes, no matter if I measure when I turn it on, start Mach3 or jog. Is that right?

Have you checked the cable you are using from the parallel part to the BOB? Check that it is wired straight through (1 to 1, 2 to 2 etc) for all 25 pins.

I will double check it today, I have checked it when I was setting up another cheaper Chinese board and I did get that to work. I tried changing the step pulse, changing to active low, changing pins. Nothing has worked yet. Dir works well. Is there anything else thats so simple I may have missed it?

Also when I view threads it is backwards, is it possible to change that? I hate starting the conversation with the last word.

cables and. connections perfect. why is Mach only putting .07 v and not 3.3 or 5v?!

Unplug the BOB and measure signal direct on the cable. The BOB may have a fault that loads down the signal.
Measure at the PC and the end of the cable. Should get the same results.

Do you have an oscilloscope? It will allow you to see the pulses. I don't think a multimeter will work for this.

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Originally Posted by jrsaw27

I will double check it today, I have checked it when I was setting up another cheaper Chinese board and I did get that to work. I tried changing the step pulse, changing to active low, changing pins. Nothing has worked yet. Dir works well. Is there anything else thats so simple I may have missed it?

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The step signal is a short pulse instead of a steady signal. You may not be able to get an adequate reading of that signal using a multimeter. Do you have access to (a friend who has) an oscilloscope that you could use to probe that signal?

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Originally Posted by jrsaw27

Also when I view threads it is backwards, is it possible to change that? I hate starting the conversation with the last word.

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Click on the User CP link near the top of the page, then on the User CP screen, on the left, under Settings & Options click on Edit Options, scroll down to Thread Display Options, change the Thread Display Options dropdown to Linear - Oldest First, click on Save Changes.

Doorknob: Thanks! that's been bugging me for a long while!

@ Doorknob and Dsnaith: I get the same readings with MM at the end of the cable and the bob. If I could find an osciliscope I could diagnose the problem but I have already tried many fixes that haven't worked, what else is there to try other than Step pulse length, Port Mode (ECP, EPP, etc), low active or my last hope is to change computer or find a printer port card that will work. I have the latest mach3, just re installed. Should I try again?
When I change dir, the motor does one step.

Through deductions I think the program or port and/or driver is at fault. then again I dont know much about it.

I decided to go ahead and purchase a hobby DSO handheld oscilloscope and learn to use it, after a few articles, manuals, and youtube videos, I get how it works and the basics on how to use it.
If I get a good waveform but low Voltage, what do I do next? or bad wave?

In the mean time I will hook up the driver straight to the cable just to see if that changes anything, maybe bad optocoupler?

If the problem turns out to be a weak parallel port, then something like this C26 - OUTPUT BUFFER BOARD may help:

CNC4PC

WRITE DOWN CURRENT SETTINGS before changing!!

Temporarily you can change the pin output to active high (or is that low) state and the pin will remain high and go low momentarily. Then just see if it has 3-5v on it.
Check what level to expect by examining a direction pin. Use jog keys to make that change state.

Yes I do have a c10 but I measured 5v out of some of the pins without so I may not need it; However when I do connect and power it the bob doesnt work. It may be a cheapo solder type patch cable and may be short circuiting. I have a better cable coming Tue.
I also dislike the c11g, it has a female port so I cannot just piggyback one board onto another, I am also waiting for gender changers for the DB25 to fix that.

@neilw20: I will do this when I get home,I have done this before to see if anything changed but what will the current tell me ?

I mean C26, not c10

I have measured the step pin as suggested and came up with .05v and even on my multimeter at 200um the current is un-measure-able. I should be getting a small hobby dso nano oscilloscope and I will get more readings from the bob and cable sometime Tue. those measurements can help me pinpoint the problem, right?

I was looking for ideas else where when I found a [ame="http://www.youtube.com/watch?v=KWAsqfduPe4&list=PL1B63A8D535238656"]youtube video here[/ame] Start at 2:40. This guy has the same board I do and the step pin lights the same as mine does. It does not light up how I thought it would but if it is just a pulse, that makes sense.

Is there a chance the drivers arent compatable? They are fairly simple, PoStep25. I will email the manufacturer today.

I think you will find with that clunk at the start the acceleration is too high, or is that a noisy keyboard?

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Originally Posted by jrsaw27

Is there a chance the drivers arent compatable? They are fairly simple, PoStep25. I will email the manufacturer today.

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Based on what I have seen in the PoStep25 manual, it ought to be compatible with your BOB (although the exact driver chip used on that board does not appear to be identified - perhaps it is one of the TI driver chips). But what jumper settings are you using on the BOB?

I expect that once you have the oscilloscope and can probe the signals at the BOB output/driver input, you will have enough information to figure out what is happening.

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Originally Posted by doorknob

But what jumper settings are you using on the BOB?

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I have nothing plugged into the outputs terminal and the jumpers are all on pull down. (I have a question about what that does but I will save it for another thread). For the inputs side, There is a jumper for COM or +5v, it is set to COM. And the last is for Safety charge pump, I have gotten it to work correctly with it on and disabled. The Drivers are set to half step and 1 amp, well within any maximums. Right now Mach is only hooked up to X enable, X step, X dir and the driver powered. In the youtube video above my Bob looks and acts exacly the same but with no movement. I tried with a different Nema 17 just for kicks too. Cant wait for the oscilloscope.

@Doorknob This is the second time you have helped me. Thank you. I probed and probed and found nothing wrong in the cable or Bob. I figured my driver must suck. before unplugging that and hooking up the probes I decided to switch Step and Dir. I tried before bout nothing. This time it went click , click, click.. I looked at the stepper, IT MOVED! The manual for my stepper has DIR and Step reversed. I will email them later and let them know, maybe it was fixed but I got wrong instructions or something, I dunno. The reason I didnt see it before was my motor tuning velocity and Acceleration was wayyyy too low. Works like a charm now. Thanks to all who inputed and answered my dumb questions.

ABC. Accept nothing, Believe nothing, Check everything.
You probably did but the manual being wrong failed the believe nothing step!!
Well done.