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Author Topic: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??  (Read 13625 times)

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Offline Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #10 on: August 06, 2008, 10:38:51 AM »
in what way? Mach is open loop so wont do anything with your encoders except display what they are reading.
Hood
Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #11 on: August 06, 2008, 10:41:00 AM »
Is there any way I can have Mach use the encoders as its point of reference?  Kinda like a servo based system?

Offline Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #12 on: August 06, 2008, 11:02:18 AM »
No not really. You could use the encoder input to cause a fault if the  position is out by a user set following error. Ron Rogers sells a board that makes this easy to do. www.rogersmachine.net
Hood
« Last Edit: August 06, 2008, 11:15:06 AM by Hood »
Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #13 on: August 06, 2008, 11:08:56 AM »
Link was dead, found it with google.

Is a servo based system closed loop?  How does that work, from a mach stand point? Sorry about the dumb questions, I have only built stepper based systems.

Offline Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #14 on: August 06, 2008, 11:16:03 AM »
Ah sorry about that, missed out the S in rogers :(

Its not what I would call closed loop. What it does is you set a limit you are willing to accept (following error) then if the position Mach thinks the machine should be is out by the amount you have set then the board will tell Mach and the programme will stop.
 Hood
Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #15 on: August 06, 2008, 11:19:06 AM »
ok, so the driver board does the work, not Mach.  Good to know.  Is there a way to get Mach to through the error, with out the aid of extra hardware?

Offline Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #16 on: August 06, 2008, 11:21:10 AM »
You could probably write a macropump or a Brain to compare the axis DRO and the Encoder DRO and if different by a defined amount then fault Mach.

Hood
Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #17 on: August 06, 2008, 11:28:02 AM »
Can I pass "jog" corrections to Mach, when there is a offset? I would guess the logic would be something like: pause, jog, start.

Offline Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #18 on: August 06, 2008, 11:39:36 AM »
Not sure, Mach as far as I know can only get its reference position (machine coords zero) from a homing routine and you cant change it. It may be possible to pause and then offset your work offset by the error amount.

Hood

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Re: Does any one have the datasheet for a HP HEDS-7500 Optical Encoder??
« Reply #19 on: August 06, 2008, 11:53:36 AM »
Thinking about it you should be able to feedhold then write to the DRO the correct position from the encoder then start again. Not sure how Mach would respond to that but it should be similar to a feedhold, jog then restart. The difference would be you have not actually jogged away you have just changed the DRO. Cant test it out as my machine is busy at the moment and after that I am off home but will mess with it after I get home as it is an intersting thought.
Hood