Encoder Opinions?

27 Nov 2021 03:09 #227722 by JackW327
Encoder Opinions? was created by JackW327
I hope this is the right place for this ...

Encoder Opinions? HEDS 5605 -v-  CUI AMT 3132? ... here's what's going on ...

Mesa 7i95 board with ENCY encoder 'wyes'.
Servo drives - Gecko G320X
Motors - Old Reliance micro 100 series. X is a 3/4 hp Nema 42, Y & Z are 1/3 hp NEMA 34s. All are 100V. Running them @ 80V
DIY linear PS - 2 x 800VA toroids -w- 3 x 18,000 uf 100V aluminum electrolytic caps (new at the time Panasonic GAA series)

Note: This is 2nd generation Bridgeport Series I retrofit & switch from Mach 3 to LinuxCNC. I first did this machine about 15 years ago. (Some of you might recall that)

Current Encoders - HEDS 5605
  • Why? Came with the motors ...
  • They need 1K pull up resistors and a 1uf cap across the power leads to work with the G320X. Gecko has an app note from 2017 addressing this. They are fussy about input power transients (hence the cap).
  • These were causing me some issues with my old G320s over the past ~15 years on the X axis (longest cable) until I recently discovered the post from Mariss @ Gecko about the 1 uF cap (problem totally solved).
  • These are the devil I know. There are a lot of them out there working fine apparently. Still made. I recently got a couple for bench testing.
Candidate encoders - CUI AMT 3132
  • These have a logic one voltage of Vcc less 0.1V and a no load current draw of 16ma and so are compatible with the G320X out of the box.
  • The resolution is also configurable in software.
  • These are relatively new. CUI just sold their millionth unit so it sounds like they are here to stay.
  • They use capacitive sensing instead of good old optical.
  • ~$37.00 each ... very reasonable.

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28 Nov 2021 04:38 - 28 Nov 2021 23:39 #227798 by JackW327
Replied by JackW327 on topic Encoder Opinions?
I got one reply on Facebook saying the guy had the the same issues & fixes on the HEDS encoders & that the AMTs work. Leaning that way more ...

Edit: Been doing more searching for info. Found one thread where someone had issues with a G320x / AMT 103 encoder & cleaned it up with a .01 uF cap across the power at the encoder.

The 102 / 103 encoders have a logic one of ~4.2V. Gecko's app note says the G320x needs 4.0 V minimum. Not much room for error. The AMT 312 / 313 encoders are at ~4.9V so that seems like the better choice still. I suppose I could pull up the 102 / 103 output ... but why?

Also ... kinda surprised there are not that many choices out there < $100 per encoder.

So nothing is perfect ... Maybe I'll just stick with the HEDS encoders and the known fixes, see how testing goes, and see if I need to make a change then ... 
Last edit: 28 Nov 2021 23:39 by JackW327.

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