parallel port closed loop

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29 Oct 2010 11:57 #4958 by billykid
Hello everyone, I'm trying to etch configuration with a servo motor and encoder with 512 pulses per revolution, and seems to be going very well.
by mounting two parallel ports I wanted to know the maximum number of rpm with 1024 encoder pulses and the maximum speed using the mesa 5i20
Regards Mauro

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29 Oct 2010 13:43 - 29 Oct 2010 13:46 #4960 by andypugh
Maximum speed of encoders or motors will not be limited by the 5i20, but by the motors and other parts, I imagine.

The max pulse rate with the Mesa cards is 6Mhz normally, and 20Mhz if you turn the filter off. For a 1024 count encoder that means 360,000 rpm in slow-mode and a million rpm in fast mode.

(23:32 here: www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2009-02-16.txt )

With a parallel port it depends on the base thread period, but assuming 20,000nS and a 2:1 sample ratio you would be looking at about 1500rpm. (which is possibly OK, it's not desperately slow)
Last edit: 29 Oct 2010 13:46 by andypugh.

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29 Oct 2010 18:51 #4968 by billykid
thanks, actually 1500 rpm are not so few ... with my driver dc in step/dir mode move to 4800 mm minute.
Regards Mauro

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03 Nov 2010 15:37 #5058 by billykid
I tried the following configuration: 77 volt 7 amp motor
1024 cpr encoder scale base period 20000 1024 4 mm round.
runs really well just do not exceed 2700 mm minutes
about 700 rpm. I have to change something to go to 1500 rpm?
Regards Mauro

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03 Nov 2010 15:47 #5059 by andypugh
billykid wrote:

I tried the following configuration: 77 volt 7 amp motor
1024 cpr encoder scale base period 20000 1024 4 mm round.
runs really well just do not exceed 2700 mm minutes
about 700 rpm. I have to change something to go to 1500 rpm?


Any idea what is limiting the speed?

What is the max velocity of the axis in the INI file, for example?

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03 Nov 2010 17:19 #5062 by billykid
80 inch minutes more than 4500 mm min .... just dropping a base_period can turn higher.

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