ABS Encoder Posital 7i92T bit file help

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16 Aug 2023 15:00 #278174 by Doug Crews
Hello all,I’ve been loaned an Absolute encoder to see if I (meaning we…!!!) can use it in our linuxcnc applications.   It’s a kit encoder from Posital.   Kit Encoder | POSITAL I’m very interested in them because they do not require a battery, and they have a very small package i.e. 22mm diameter.  A few months back I was quoted $168.00 US  for the 22mm simple version which is not that much more than a kit an incremental kit encoder from US Digital.I have a development panel powered and running the following:   
RPI 4  running 2.9  (thank you elovalvo)
7i92T
7i77I can see the inputs responding to a basic xyz pnccofig,  so it's ready to go.No drives/amps yet.  Also, 7i70 on standby if needed.I’m hoping to just establish and verify communications enough so that I can order some these with confidence they will work. I’ve attached the data sheet.  It’s a binary type.  multiturnI need help with a bit file for the 7i92T,  and most likely the hal file if I can’t muddle through it.It would be great if the encoder terminal blocks on the 7i77 could be re-allocated to accommodate the clock and data pairs,  The preset and config may not need to be connected, I’ll find out.Thanks in advance for any help. Doug
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16 Aug 2023 16:43 #278181 by PCW
What interface does the encoder have? (SSI,BISS, etc?)

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16 Aug 2023 19:19 #278196 by Doug Crews
Sorry Peter, I thought the pdf file attached.

Its, binary SSI  multiturn.   maybe  the attachment took this time.    

-Doug

 

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16 Aug 2023 21:42 #278203 by PCW
I can make  bitfile for that but it requires a RS-422 interface
(say a 7I74 or 7I85) . You could use the serial expansion port on
the 7I77 to test 1 channel with firmware that puts a SSI interface there.

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16 Aug 2023 21:56 #278205 by Doug Crews
Ok thanks for clarifying. Sounds like I may not need a unique bit file. It all gets done in Hal?

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16 Aug 2023 22:07 #278206 by PCW
No, you need specific firmware to support SSI (or BISS or whatever)
encoders.

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16 Aug 2023 22:32 #278208 by Doug Crews
Ok understood, I don't want to cause you any extra work for a potentially one-off project on the 7i77. the 7i74 is in stock I can get one of those coming my way if you already have firmware written for them.
-Doug

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16 Aug 2023 22:53 #278210 by tommylight
There is firmware for 5i25+7i77+7i74 for SSI absolute encoders here but do NOT use it with 7i92:
forum.linuxcnc.org/30-cnc-machines/31792...rofit?start=60#86415

There is also a config attached on the first post, this might help with setting stuff if you have SSI encoders, has 6 of them on the Mesa 7i74 and two SSerials left for other stuff.

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16 Aug 2023 23:00 #278211 by PCW
I would need to make firmware for the 7I92T as no SSI firmware exists for it.
but its not a big deal, just some copy/paste and recompile. Do have an idea
of what daughterboards/pinout you want?

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16 Aug 2023 23:26 #278214 by Doug Crews
I'm trying to emulate the 5i25-7i77 2x combo up to 12 axis. . (its been working real good for me) But instead of the 5i25 I'm using the 7i92t and whatever else makes the most sense. If go with the 7i74(s) It seems would need something else for servo-enable and analog/pwm. I'm totally open to suggestions.

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