Messages

1

General Mach Discussion / Re: Digital scales as input?

« on: October 18, 2006, 02:38:20 PM »

Are you doing this in an attempt to get mach to close the pid loop for positioning? If so then sorry will not work, mach spends most of it's time worrying about a steady pulse train out to the motors. It doesn't have enough time to do high speed pid loops.

Yes, this was my intention.

The other problem with using encoders on the axis and not the motor/servo is if there is ANY backlash in the mechanical then a pid driver will cause the motor to constantly hunt and eventually burn it out.

Some algorythms can handle this, if they don't insists on getting exactly that position.

If you just want to use these as a dro for manual machining then a plug in probably could be written just to display position but it probably would be easier just to write your own little dro app.

OK. That app already exists. I just thought the interface could be used for loopback too.

Thanks,
Nick

2

General Mach Discussion / Re: Digital scales as input?

« on: October 18, 2006, 09:08:51 AM »

I wonder if you could set those up as encoders in ports and pins?

Would be quite a pain. The signal is serial, that's why I feel that some kind of software-plug-in would be best (if that is doable).

What kind of signal do those give?

Each channel (4 channels, one scale per channel) gives a response when asked (when a command to read is sent to the interface). The response is raw data (in hex) that needs some decoding (to interpret the flags coming from the scales etc.).
The response looks like this:
DRO#1L:<someHexData>

That data has to be converted into an integer and then scaled (20480 steps per inch or 100 steps per mm for an other type).
That decoding is currently done on an PC that works as a DRO.

Nick

3

General Mach Discussion / Digital scales as input?

« on: October 18, 2006, 08:31:19 AM »

Hi!

I am new to this forum and -I have to admit- a complete Mach-dummy!

My main reason registering here is, that I have built an interface that connects to 4 "cheap chinese scales" and on the other end communicates with an PC over RS232.
What I'd like to know is, whether there is a way to integrate that interface into Mach. I tried to find that out but was more confused after than clueless before.

I know the scales are slow (30 values/second), but if you think they are of any use, I'd like to write some software plug-in or change the firmware if necessary. If only someone could push me in the right direction.

Thanks,
Nick