On Wed, 29 Nov 2017, Gene Heskett wrote:
Date: Wed, 29 Nov 2017 23:41:51 -0500
From: Gene Heskett <[email protected]>
Reply-To: "Enhanced Machine Controller (EMC)"
<[email protected]>
To: [email protected]
Subject: Re: [Emc-users] omron encoders
On Wednesday 29 November 2017 22:42:11 Chris Albertson wrote:
So the spindle spins about up to about 3,000 RPM. That is 50 rev.
per second. You have a 1,000 line encoder so that is 50,000 lines per
second on each channel. You should seeing a 50 KHz square wave on
both A and B channels. I don't understand the 1.8 MHz reference.
Theres some ringing on the edges that my fauncy digital scope may be
counting. But your math is wrong, the way its hooked up its a
1000*7161.17=761,170 line/rev, * 3000=38,058,500 hz. I do believe thats
a bit much for a 5i25 to process.
If the encoder is on the motor, whats the maximum motor RPM?
If its 3000 RPM (50 RPS) the maximum output frequency is 50 KHz
(50 RPS *1000 lines) or a 200 KHz quadrature counting rate.
This means the pulse width will be approximately 10 usec at 3000 RPM.
For filter setting, to accomodate deviation from perfect square wave signals,
its a good rule of thumb to set the input filter so its time constant is about
1/2 of the input pulse width at full speed = 5 usec. So for example you could
set the encoder sample rate to 3 MHz and enable the encoder filter (15 counts)
this would be 5 usec.
Note that most quadrature encoders output frequencies are limited to
500 KHz or less due to optical sensor bandwidth.
As far as count rate limits go, the 5I25 can have a encoder sample rate of 33
MHz, and with the filter off (3 counts) this means it will recognize input
pulses longer than 90 ns so could theoretically read quadrature count rates up
to about 20 MHz but I dont think there are any quadrature encoders that
fast...
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
------------------------------------------------------------
------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
Peter Wallace
Mesa Electronics
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
