Mesa card and absolute encoders.

I'm designing a 6 axis robot with the intent of using absolute encoders on all axis and am wondering what type of absolute encoders can be interfaced to mesa cards and Linuxcnc? From bit of googling I gather that SSI encoders can be used but can SPI or RS-485 encoders?. I'm thinking of using the following encoders:
ams.com/as5048ahttps://ams.com/as5048a
CUI AMT-21 series
CUI AMT-23 series

And how would they be interfaced? Through a 7i44 board? Or can the 485 encoders be used with just the RS-485 interface?
Im thinking of using the 7i93+7i44+7i47 combo.

There's no direct support for SPI encoders in HM2
SPI is not a great long distance protocol, I'm pretty sure those
SPI interfaced encoders are intended for applications where
the SPI link communicates with a local (inches away) microprocessor

It seems I'll go the SSI encoder route then. Would it be possible to use a different ethernet card for the encoders only? Something like a 7i94 for the encoders and another board for step generation. Id like to keep the cabling to a sensible level.?

Also I've used those spi encoders before and they do work fine with 2m cabling. You can also extend spi to a degree with lvds.

You can use multiple Mesa Ethernet cards (up to 4 currently) with LinuxCNC
You would want a fairly fast host CPU to use multiple cards

How fast are we talking about? I've been thinking about using something like a RPI4 or intel NUC(or other small machine) to run Linuxcnc since i don't need graphics performance to drive the UI.

Mostly Linuxcnc would take care of the motor control loop and maybe some light kinematics down the line(I already have ROS for complex planning) and to make and run programs.

I would probably say I3 or better

Hi PCW,

I am thinking about to change my incremental encoders to absolote Heidenhain linear encoders. Would SSI work on all SS ports or only on the RS422/485 boards. can you maybe share a FPGA config file for SSI? this would be very helpful to understand the cofig on the FPGA side.

Typically SSI encoders have a RS-422 interface, so if you have a 7I44,
that would work. I don't seem to have a SSI example hal file here but I may have
one at work.