Fanuc Serial Pulse Coders - Red cap servos, mesa 7i76e, how to?

Bennett wrote:

My other option would be to output TTL incremental encoder pulses from LinuxCNC (is this conversion from absolute serial encoder data to TTL incremental possible?)
 

Yes, Pico Systems makes a board that converts most Fanuc serial pulse coders to quadrature with index and commutation signals.  One detail to note is that with high-resolution encoders, the quadrature count rate can become very high.  Another detail is that these encoders can't be interrogated faster than 8 KHz.  See : picosystems.store/product/fanuc-serial-e...nverter-pulse-coder/  for more details.
Jon

Thanks for chiming in. I'm hopeful that this is not the solution I'm after. My goal is to convert these signals within LinuxCNC using something like the BLDC HAL component or something of that nature then spitting out the results via some of my available outputs on my Mesa cards. Surely Hopefully it can be done in HAL and not need an external converter board. These PICO boards would hurt the wallet too much as well, 600USD for 4 that's 850CAD and that's about half of my net worth

#machineShopOnAShoestring

Could StepGen be used to convert the absolute position data from the Fanuc encoder channels to quadrature pulses for outputting to encoder input on the drives? 

The image below is where I'm getting the idea to use Stepgen to convert my fanuc encoder data to AB quadrature for outputting to the drives, but I could use some insight as to whether or not it will function or if I'm missing some important details.. Does anyone know?  



Within the HAL, is there a possibility of connecting the fanuc encoder data position output to the 'position in' port of Stepgen as it runs in quadrature output mode, to then output the quadrature pulses to my AB Ultra3000 drives to provide the position feedback to them? Or is there some major flaw in this concept.. 

Thanks

This very quickly is going to turn into a how to destroy some Fanuc encoders thread so stay tuned for that   

I've decided to replace the encoders... this is probably not the answer that future readers are going to want to read, but its the least expensive and most straight-forward approach I can come up with. Either I have a digital problem or a mechanical problem to solve, and the latter is much more manageable with my skill set. 

I'm trying to get better at knowing when to take a different path to the finish line. I once spent months trying to design a DC motor driver (90v 200amps) that ran on 600v 3phase for a Hardinge CHNC lathe based on open source electric vehicle schematics. Long story short, I didn't succeed and blew up a lot of expensive components along the way    Once I finally decided to swap the motor for an AC one and add a VFD, the whole thing was turning in in 2 days! 

More to come! 

I had red encoders on the two servos I was using but changed them for 1024 a b z encoders. They weren't compatible with the mesa card I bought- i thought they would be.  Was a lot simpler with standard encoders even with the startup positioning.

That's what I'm starting to realize! Thanks for adding to my confidence on this route.

I have found some good encoders - I'm thinking of going with 10000 PPR for X and Z and 800 PPR for the turret and the live tooling motor as the latter won't need much in terms of resolution, while the Z and especially X will need as much as I can get/afford (maximum count rates of A-B Ultra3000 2.5 mHz).