Looking for advice? Is my DB25-1205 breakout board faulty?

Hi all,
I'm just setting up my home-built CNC machine. I had the stepper motors turning a few months ago on the bench via a PC running LinuxCNC and a DB25-1205 breakout board.

However, now I've put everything together properly the X and Y axis won't turn via the LinuxCNC software.

This is how far I've got.....

My machine has 'manual' functionality built-in via an Arduino board.

I can 'manually' turn the X, Y and Z in both directions fine.

If I start up LinuxCNC I can operate the Z axis through the software fine.

If I try and operate the X or Y axis the values change on the PC screen but the actual motors don't turn.

If I connect the X axis direction/pulse wires into the Z axis connectors on the breakout board and then manually operate Z in the LinuxCNC software then X works fine (which proves all the wiring from the breakout board to the motor).

So... I'm looking at either a setting or a problem with my breakout board?

I am an absolute beginner with all this. I mean it is ALL new to me so if you can give me any advice I would be very grateful. I've attached my StepConf settings for you to cast an experienced eye over.



Many thanks

John

if nothing else, the stepconf settings look fishy

If your drive has 10 usteps/step , steps per revolution with a normal step motor should be 2000 not 25000

andypugh wrote:

This is often a problem with the "enable" pin on the drives

Are the not-moving motors locked or free to rotate?

free = no enable signal (or positive disable signal)
locked = no STEP pulses or STEP pulses too short (or wrong polarity)
turning only one way = no DIR signal.

Having enable, dir and step switched around can have a variety of effects, sometimes even almost working.

Hi Andy

The 'not moving' motors lock as soon as I put power on them. Do you mean to swap the signals on the StepConf software? Or remove the 'invert' bit? Or do you mean to physically switch the connections on the breakout board?

This fault confused me because when I put the X Axis dir/step connections into Z then X would drive correctly (by manually driving Z in LinuxCNC). That to me says that the dir/step are the right way around on X (because they are the same as Z) and that the 'invert' bit is correct (because it's the same as Z).

Is this not the case do you think?

Thanks very much for getting back to me. Much appreciated.

Another possible issue is the slowness of the DB25-1205 outputs. These are known to be marginal for step outputs. You might try increasing the step time.

PCW wrote:

if nothing else, the stepconf settings look fishy

If your drive has 10 usteps/step , steps per revolution with a normal step motor should be 2000 not 25000

Hi PCW

To be honest I can't remember where I got those figures from. I think I took them from a YouTube video many moons ago.

The history to this is that I started building the machine January 2017. I managed to get the control board etc finished around May '17. But then, due to other stuff, I didn't get the actual frame finished until a few weeks ago. So this is me just trying to find my way again through it all.

I'm not from a CNC background at all. I've never used Linux before (let alone LinuxCNC). I've never used a CNC machine before.

I'm a PLC software/electrical guy so I'm really a monkey on a new tree with all this.

The drivers are DQ860MA
www.wantmotor.com/product/dq860ma.html

The motors are Stepper Motor 8.7Nm Nema34
www.cnc4you.co.uk/Stepper-Motor-8.7Nm-86HS115-4208-Nema34

So, any advice on correct settings would be very much appreciated. Thanks

PCW wrote:

Another possible issue is the slowness of the DB25-1205 outputs. These are known to be marginal for step outputs. You might try increasing the step time.

Hi PCW,

I did try putting my meter on the 'dir' output of the board and it just sat at 5V (4.89VDC to be exact).

The Z axis changed from 0 -> 5 V depending on direction but the X didn't change when I manually tried to move it in the software.

That's what was leading me to settings or the board (or something else???). But I'll try adjusting the 'step time' just to see if it changes anything. Thanks for your continued help

John

Yeah if direction does not work that suggests a software setup (wrong pins in stepconf?)
hardware setup (breakout board options), wiring or hardware fault

PCW wrote:

Yeah if direction does not work that suggests a software setup (wrong pins in stepconf?)
hardware setup (breakout board options), wiring or hardware fault

Is there a hardware setup for those breakout boards do you know? I don't remember setting it up?

I'll have a mess around with changing the step/dir outputs and see what happens.

Thanks for all your help

This card will work with LinuxCNC but it is slow...

I would have a good look at your stepper driver documentation. I have a feeling steppers need to be wired differently to how its done on an Arduino. I think they need to be set up as active low. Thats something I made a mental note of when I was working out how the card might work but I've never tried past testing that the outputs worked.