Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: markn on April 17, 2014, 12:05:08 PM
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Hello All,
I have a newbie question, As I understand, Mach 3 can read encoders an send that information to the DRO's and that this will require the use of the second Parallel Port configuration. I am not sure of the resolution of the encoders, although there is a label stating .01mm. How do I find the resolution of these encoders and will the PP interface be fast enough to catch the pulses from the encoders. This will be used in a manual operation.
Thanks
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Your resolution will almost certainly be 0.01mm if it states that one them.
Will the PP be fast enough?, well that depends on the Velocity your axes will be set to. I would not hold out too much hope of getting reliable results above 25KHz, so with the resolution of the scales that would equate to 25,000/100 pulses per unit (1mm) = 250mm/second or 15m/min
Its been a long time since I fed encoders into Mach so not sure if it will be quad, if so then the max velocity at 25KHz would be 15/4 = 3.75m/min
Not sure what you are planning on doing with the encoder feedback but I imagine you do realise that Mach itself will not act on the info for the trajectory, ie no closing of the loop.
Hood
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Thanks Hood,
I was hoping to use the readouts in a manual situation not close the loop. I am retro fitting the existing DC servo motors with encoders to work with Viper drives to work in a CNC function but would like the option of using the DRO's for X,Y and Z axis with the servos off. Arturo mentioned adding a Smoothstepper board for the purpose of reading the glass scale encoders as he was unsure that the PP would be fast enough.
How would this work?
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It would work to a certain extent, ie the Encoder DROs would change with the scales however the axes position DROs would not. In other words you could use the Encoder feedback as you wish but to switch back to CNC you would have to rehome so that Mach once again knows where it is. You could, I suppose, have some VB in a button to check position and update the Axes DROS when you switch back to CNC rather than homing but probably just simpler to rehome.
There are a few external controllers that can take encoder feedback and use that to update the axes DROs so that even manually turning the axes the position DROs in Mach get updated and thus Mach always knows where it is, one being the CSMIO/IP-A that I use on my Chiron. These controllers tend to be for analogue command drives rather than step/dir, the Hicon however may also be capable of this and it is Step/Dir but check to make sure if you want to go down that route as I have never used one, so cant be 100% certain.
Hood