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encoder interface specifics
« on: June 16, 2006, 04:34:09 PM »
Hi all

I am new to this encoder business - I have run steppers without them for years with no problems.

I am considering the following:

An encoder (a 300 cpr model from US Digital  - 1250 ppr ) on my X and Y motors that requires 400 steps per inch
When an EStop signal is sent my control sets the motors to free wheel - no voltage is applied to the motors at all
I use this free wheeling state to reposition the machine (It is a sewing machine - not a mill - its is in the garage)

Now the "I hope to" section:
I cause an EStop
I move to a position and zero out the system and it hopefully zeros the encoder DRO
When I get to the new position I would like to see the DxDy coordinates in the encoder DRO

My question is:
Because the EStop condition existed before the attempt to zero and then the move of the machine, will the encoder DROs still function properly or will they be blocked due to the EStop condition ?

any thought on this matter would be greatly appreciated
Re: encoder interface specifics
« Reply #1 on: June 16, 2006, 05:54:37 PM »
I have not tested this but I think it can be done... You are only going to be able to read at 8KHz from the printer port so keep that in mind. Also to get this working you are going to have to do some VB coding...
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: encoder interface specifics
« Reply #2 on: June 16, 2006, 06:41:57 PM »
I don't thing the 8K read rate will be a problem -
I usually sew at 60 IPM but if I move the sewing head at 200 IPM with a 400 steps per inch (1/2 revolution) motor that is only 1.3K -
I guess 1250 pulses / rev on the encoder would generate (worst case) 2K pulses which would need to be read.

What VB coding are you speaking of ?

I did some for my M6 command - seemed rather straight forward.
And I will have to write some to be able to look at the encoder values and stretch / rotate to tool path accordingly. Cloth stretches and
Quilters are not an exact group - especially considering the finest graduation on their measuring device is 0.125 :D
Re: encoder interface specifics
« Reply #3 on: June 16, 2006, 09:13:42 PM »
You will have to write some code to set the Pos of the motors in Mach3 to the pos of the Encoders when you move the axis by hand. This should not be that hard to do... Just add code that can read the encoder pos and set the Mach3 pos when the button that enables the drives is pressed. should be that simple  :)
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: encoder interface specifics
« Reply #4 on: June 20, 2006, 09:05:03 AM »
Brian,
   Ron Rodgers has a board that will read the encoders and has the script for a micropump
to work with it.
Jim