Mach3 + Modbus Experiments

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Mach3 + Modbus Experiments

Postby bdring » Tue Feb 01, 2011 1:29 pm

Here is a write up on a one evening experiment to use Modbus to help control laser power using an Arduino. I think it shows promise. An Arduino is less than $20 and requires no extra parts to do this job.

http://www.buildlog.net/blog/2011/02/mo ... ins-oh-my/
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Re: Mach3 + Modbus Experiments

Postby lasersafe1 » Tue Feb 01, 2011 5:43 pm

Looks very interesting. I remember spending hours experimenting with Mach3 and trying to get the darn laser to turn on and off without pausing the move as it does when you make a Z move. Clearly the modbus could handle the laser fire bit. I'm doubting that it can be used to slope the power with speed since the power settings on these Chinese supplies are not very linear.
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Re: Mach3 + Modbus Experiments

Postby gavztheouch » Tue Feb 01, 2011 7:15 pm

Looks promising,

"I'm doubting that it can be used to slope the power with speed since the power settings on these Chinese supplies are not very linear."

Could we write an algorithm to compensate?
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Re: Mach3 + Modbus Experiments

Postby bdring » Tue Feb 01, 2011 7:46 pm

Acceleration compensation: It would only come into play on axes with really slow acceleration rates like a mill conversion or a heavy gantry machine. The "Brain" update interval is at best about 25Hz. If you have a light machine, like most of ours, the acceleration is at least 100 in/sec/sec. If you have even a really high cut speed of say 10 in/sec, by the time the laser reaches full speed the number of changes is going to be 2-3.

I was just throwing out ideas to start discussions.
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Re: Mach3 + Modbus Experiments

Postby gavztheouch » Tue Feb 01, 2011 9:44 pm

Bart are you using the Uno/Duemilanove board, ie the cheapy one. I have been wanting to buy one for some time, now It looks like it might have a practical use for this project I might make a purchase. Is it right that the standard £20 board is programable using only a usb cable, so you don't need a devolopment board or other hardware to download your program to the chip? Seems like a bargin at 20 quid.
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Re: Mach3 + Modbus Experiments

Postby lasersafe1 » Tue Feb 01, 2011 10:42 pm

In case anybody here in the states is interested, I have a Duemilanove and the 3.2" touchshield slide that I would let go for about $80.

http://www.liquidware.com/shop/show/TSL ... ield+Slide
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Re: Mach3 + Modbus Experiments

Postby bdring » Tue Feb 01, 2011 11:59 pm

The boards with USB are direct programmable and then the USB can be used as a serial connection the PC. So the Modbus worked right over the USB.
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