Stepper lose one step if direction is changed

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07 Sep 2012 11:24 #24010 by sk800s
Hello

I've a problem with my Steppermotors on all axis.
The driver is directly connected to the paralell connector of my computer.

All seems to be right. The axis turns in all directions.
Now the problem. Even if the direction turns the axis seems to lose an step.
For example - i go to the configuration of an axis. I write down the parameters an then i test the axis. I said go right/left for 30mm. The axis now turns right an left, but the axis moves slowly more and more to right direction(it seems to be one step per change of the direction). If i invert the direction signal in the stepperconf and i start the test, the axis always turned from right to left but the axis now moves slowly more and more in the left direction. It is an electrical problem. It seems the the last step befor the direction change go in the wrong direction.

Has everyone a idea? is it possible an problem from linuxcnc or a timing problem?

Thank's

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07 Sep 2012 12:54 #24016 by BigJohnT
What stepper driver do you have and what timing are you using for step and direction?

John

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07 Sep 2012 17:12 #24033 by andypugh
sk800s wrote:

Has everyone a idea?


One offf-the-wall suggestion is that you might have step and enable wires swapped.

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07 Sep 2012 17:25 #24034 by PCW
Also step polarity may be inverted

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07 Sep 2012 18:08 #24035 by sk800s
Thank's for answers.

What is my Constellation.
I've stepper motor drivers that are equal to MBL600 by ANAHEIM AUTOMATION.
The technical data are
1. positive clock input (intern pulled down to gnd)
2. positive direction control (intern pulled down to gnd)
3. min pulse length 15000ns (15us)

First of all i connect the drivers directly to the parallel connector of my computer.
Now i say in configuration wizzard "Test my axis" an give them a way of 30mm. The axis is move from left to rigt - right to left (and so on). All seems to be o.k. - but if i control the way of my axis i notice the the zero point of my axis moves.
for example the zero point moves right. If i invert the strobe signal (with the stepper configuration wizzard) the zero point moves left.
It's minimal but after a while it sumed.

Now i have associated a interface board (China HY-JK02M) to the motor drivers. The failure is still the same. I've changed the pinning from the parallel port to the bord. Not the solution. I've tried an other interface - nothing. I've tried an other computer - nothing. I've tried pulldown resistors connected at step and direction to ground - nothing.

I've tried various values for steppiner timing.
step time -> from 15000 - 25000
step space -> from 15000 - 25000
direction hold -> from 15000 -500000
direction setup -> from 15000 - 500000

At the moment i've no idea what can i do.

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07 Sep 2012 18:29 - 07 Sep 2012 18:32 #24036 by BigJohnT
Is this your drive?

www.anaheimautomation.com/manuals/steppe...%20Users%20Guide.pdf

Does your drives have the jumper set for step and direction or CW/CCW pulse input?


John
Last edit: 07 Sep 2012 18:32 by BigJohnT.

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07 Sep 2012 19:25 #24039 by PCW
Have you tried inverting the step pulse?

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07 Sep 2012 19:46 #24043 by sk800s
No.
I've wrote to arnheim few weeks ago. They answered an say, that my driver is equal to MBL 600. My driver is an aa2901. It has the same connectors and looks like the MBL 600 but without any jumpers.
Between my last post here i have do some other tests.
I have connect between my computer an the driver an inverter 74LS04 (for x direction and x strobe). The problem is still the same. But i have notice something else. The x axis steps in one direction without x strobe is present. The cable is not pluged in and the x strobe on the driver is pulled down by an resistor. Only x direction is pluged in. What is that? It seems the arnheim driver is the problem - but why?

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07 Sep 2012 20:03 #24046 by BigJohnT
Do you know if the aa2901 is step and direction or cw/ccw drive?

John

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08 Sep 2012 07:18 #24056 by sk800s
The aa2901can do both but there are no jumpers on the board. Only a few bridges but without labeling.

General question
My machine seems to be moves right. Is this also possible if the mode of the drivers a wrong?
What will be happen if i control the board with step / direction pulses and the mode of the board is cw/ccw?
Would the machine then run at all?

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