Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: asparaguy on March 29, 2008, 05:07:01 PM
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Are the resolver to digital converter boards on the market compatable with mach.Or should I just start shopping for lineir encoders. thanks Al
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What is the linear encoder for?
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It a large vmc I have resolvers on xyz, galil 1880 card
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So you want to use linear encoders instead of rotary encoders on the motors? Right now you have resolvers on the motors that feed into the Galil?
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right now it is not upgraded. I picked up a 8080 galil on ebay.currently there are resolvers.I understand that mach does not do resolvers.So I'm considering these resolver converters on the market.The question is is it worth it.this machine has 24x40 travels so linear encoders are not 25 cents each.I would appreciate any input.Currently shopping for the same.The spherical newals are off patent but finding who else makes them is my chore for today. thanks Al
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I have been keeping an eye out in the hobby community of any news of some one using dual feed back to a cnc controller ie rotary and linear encoders and have not seen any. I think the most practical solution is rotary encoders on the motors for the cnc controller and if you want to add linear scales as a DRO to verify positioning you can do that.
Here is a controller that will handle resolvers with Mach3:
http://dynomotion.com/
Look under videos.
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I think It's solved the galil will take this kind of signal. hopfully it will get back to mach
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You mean the Galil will take a resolver signal? The only thing that can go back to Mach3 is a quadrature encoder pulse but is only use to keep track of position not a real time closed loop servo system the Galil card closes the loop between it self and the resolvers/ motors.
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Heres what it says in the siemens 810 manual the signal is a +-A,+-b,+-indexer, pulse.This is quadrature I believe?But this is 1989 equipment so It may be different than current standards.Correct me if i'm wrong I don't want to go to far down the wrong road.I do intend to close the loop with galil and use the coml for misc. i/o thanks AL
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Your signals sound like complementary quadrature. The Galil controller will accept that. Galil does not natively accept resolver signals. A search of their web site comes up with several hardware options for resolver input, but I don't think that You will need them. The giveaway is the marker pulse or +-I. a resolver wouldn't have that.
Kenny
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thank you for the advice. the next question is.Can this signal be split?What I mean is use only the +A+b index to close in mach also
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asparaguy,
I use the a+ & b+ inputs to the Galil. If You have a noisy (electrically) signal, then the complementary outputs will help considerably. On the Galil I wire the encoders to the main encoder and in the Galil plug-in configuration under "motor config" I make sure that both boxes are unchecked. That allows my encoder signals to feed directly back to Mach DRO's.
Please note, there are some areas where the Galil needs additional work in order to be fully functional under Mach. Several people are actively working to improve the plugin to round out those remaining features, so that we can all use Mach fully. Mach and Galil rock!
Kenny
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You have regular quadrature encoders that are the same standard as today.
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Hi there, I thought I would add my two cents here...
the Galil will accept quadrature differential inputs from an encoder....has nothing to do with mach3....you are supposed to be able to have dual encoders with the galil...depending on which one...and as I understand it the secondary...usually linear encoder does not come into play until the galil has used the motor encoder to make the move, then the secondary encoders makes sure you are there...supposed to be good if you have backlash in your system...I have not tried this, but I have used single encoders on a VMC with the encoders on the motors and a lathe where I replaced the resolver/tachs with encoders on the ends of the leadscrews...(hardinge hnc)
I think I would replace your resolvers If I were you...you could look at automationdirect.com for encoders the seem pretty cheap....the ones I got for the Lathe were $70 or so each....hope this helps....Roo
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Thanks for the help guys .This is starting to look like a good plan. the Galil site states (the newer controllers have added commands for counting position) What newer is I dont know.
This is for losing steps as I read but Im still two or three months off real start.I live in northern MN, waiting for snow to melt and building a garage this machine will fit in comes first. Al
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I have a 4080 galil controller and am very happy with it. My mill knee is controlled in dual loop
mode it is called in Galil speak DV. The primary encoder( a glass scale) is connected as the normal feedback.
An additional encoder the motor is also in the control loop. The problem I am having is the DRO in
Mach3 seems to display the aux encoder instead of the main encoder. I have an independent DRO that
shows the inherent back lash of a typical system. This is why I know that Mach3 is displaying motor counts and
not true scale counts. I don't know if this is a Galil configuration problem or mach 3 encoder assignment problem.
I am leaning towards Mach 3 because independent galil moves are really repeatable vial the scale DRO.
ANY HELP?
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This is a somewhat confusing setup to be sure. With Galil, you need to have the position encoder connected to the main encoder input and the auxiliary or motor encoder connected to the auxiliary encoder input. You will then need to make sure that the Galil is permanently in DV mode. You can do this via a burned in program with #AUTO as the first line, or use the notify outputs in the Plugin to be sure that the Galil DL survives a reset. You will also need to redo the axis tuning as the encoder counts have likely changed with the dual loop setup. When all is set up properly, You will have a very smooth system with excellent positioning.
Regards,
Kenny