Pulse unit

Discussions and help on this commercial controller.

Moderator: twehr

Pulse unit

Postby Greolt » Sat Feb 25, 2012 4:25 am

I have posted the following on the LightObject forum.
Some members here may not visit that forum.

AWC 608
Main Board 8.12.01.28
LCD Board 5.12.01.05
LaserCAD v5.85

I come to laser from the CNC world. In step and direction motion control, steps are referred to as "steps per unit" (step per inch or steps per mm)

On the AWC608 it seems to be otherwise. "Pulse unit" is how it is shown on the manufacturers parameters settings. However it is in reality not steps per unit. It is some other thing.

My X and Y axis are designed and built to be 1000 steps per inch (39.37 steps per mm). But entering 39.37 in "Pulse Unit" leaves it way out, in distance travelled.

In fact I must enter something like 25, to make it travel the commanded distance.

So what is "Pulse unit" ? I have even heard it referred to as "pulse width". Very confusing terminology, normally refers to PWM.

The first thing others will say is, you have your calculations wrong. That's what I would say. :) The calculations are not wrong.

I have been running this laser up till now with Mach3, which I am very familiar with, at 39.37 steps per mm.

So can someone set me straight. What is "Pulse Unit"?

Greolt
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Re: Pulse unit

Postby mattrsch » Sat Feb 25, 2012 5:15 am

On the AWC-608 "pulse unit" refers to the distance per step in micrometers. If you are set up for 1000 steps per inch you will need to enter about 25.4. Tim Wehr made a fantastic setup guide for an earlier version. All the settings are mostly the same for the 608. Check it out on this page: http://www.buildlog.net/wiki/doku.php?i ... controller

setting up my laser would have been way more work without Tim's documentation. Thanks, Tim!
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Re: Pulse unit

Postby Greolt » Sat Feb 25, 2012 6:55 am

mattrsch wrote:On the AWC-608 "pulse unit" refers to the distance per step in micrometers.


OK distance of one step in um. Therefore 25.4 make sense.

Thanks for that Mattrsch.

I have looked at some of Tim's stuff. The link you provided does show a more recent version than I had seen before.

However even though it is better than the older version, there are still many differences with the AWC608. Terminology is different and some settings shown are no longer available.

This is what it says about "Pulse unit", " Pulse Unit is the length of time that the pulse is sent to drive the stepper motor." Which is obviously no longer the case with my version.


The next question or observation I had was to do with the "Pulse unit" setting for Z axis. I need a setting of 0.432. The system will not allow a setting below 1.

This is no big deal because it is the Z axis, however it seems silly not to be able to set it to a correct value.

Greolt
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Re: Pulse unit

Postby a542002 » Sat Feb 25, 2012 10:20 am

Hi greolt,
I know it is a bit confusing but thats how it goes:
the puls unit in the AW608 is used to define the correct pulse units from the DSP given to the stepper driver and is calculated by the DSP.
for instance I make a square of 25mm in lasercut then cut them and measure the actuall measurments are and put them in the manufacturer settings in and the DSP calculates right a way the required puls units for the whole system in order to get the right measurments and position.
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Re: Pulse unit

Postby Greolt » Sat Feb 25, 2012 11:15 am

It is confusing but only because it is poorly named or labelled.

If it was called "distance/pulse in um" then it would not be confusing at all. :)

Greolt
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Re: Pulse unit

Postby iGull » Sun Mar 25, 2012 11:37 am

Hi Greolt

Greolt wrote:It is confusing but only because it is poorly named or labelled.
If it was called "distance/pulse in um" then it would not be confusing at all. :)


LOL, just read this - I had the same thing :lol: If only our Chinese was as good as their English :lol:

I have a language file that I modified to English that attempts to get rid of the 'Chinglish' (for want of a better phrase) so it is simpler to read (it also modifies Amerikans as well - tomatoe to tomato etc :lol: :lol: :lol: )

FWIW, I changed 'Pulse Unit' to 'uM per Step'. Anyone that wants a copy of my current English-UK file is welcome. It would be easy to create an English-US, English-Aus (English-Scots even ;) ) from this file by simply having a translation list - 'optimize to 'optimise', 'center' to 'centre' etc There are a few other simple things to make it more easily readable - stuff like Mirror Horzontlly to 'Flip Horizontal' etc
There are a couple of downsides to this, firstly, when someone refers to a setting where it is named differently from the original or secondly (worse), if the programmer decides to change the file structure.
Perhaps a single source for those files would be best available at the lightobject website (you listening Marco ?).

Cheers

Neil
EMOs are a sign of weakness ...
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