upgrading PUMA 762 arm

btvpimill wrote:

1) each joint has an encoder and a pot. From what I can tell, the pots are for a rough absolute position so it can home in 1 rev of the encoder. Will there be a way to support this?

That sounds like a bit of a challenge, a challenge in two parts. First you have to get the analogue voltage into LinuxCNC, and then you have to get LinuxCNC to understand what to do with it.
You can probably use the Arduino comp as a relatively easy way to read the 6 analogue voltages, though there is a dedicated Mesa analogue input board too. Some Mesa cards have analogue input configurable on certain pins too, though I don't think that any have 6 inputs.
Persuading LinuxCNC to home to the pot+index sounds interesting. One option might be to use the analogue voltage as position feedback until the joint is homed, and use home-to-index. The switch the feedback (using a mux component) when the is-homed pin goes true. The question there is whether LinuxCNC can cope with an offset home. (What you would really need to do would be to direct a rounded-down verson of the analogue sensor position to the motion module as the HOME_POSITION, but I don't think that is possible).
If that can't be made to work, then you may need to add an integer number of revs to the feedback position. This may be tricky with f-error checking.
You might be able to integrate the pot values into Pumakins.

2) All 6 joints are rotary, so any ideas what "axis" will need to be assigned? can I call XYZ or UVW angular instead of linear?

You need to make a distinction here between "Joints" and "Axes". Your robot has 6 degrees of freedom, the position of the actuator in XYZ space, and the angle of the actuator in ABC.

You control the actuator position in XYZ linear space, anf the Pumakins module does the clever stuff of calculating what joint angles are needed to put the actuator at that point in space.

btvpimill wrote:

Now it says it connects to anything IO cards, but does this also include the 5i25?

You will need a 5i20, 5i22 or 5i23.
In theory a special firmware for the 5i25 and a special cable could make it work, but why?

The 5i25-compatible servo card is the 7i77. However this only has 4 analogue inputs, so won't do what you require quite so well as the 7i65.

btvpimill wrote:

well in reality, not sure how well we will be able to use the pots on the arm anyway. looks like the 7i77 will do everything else. And if we could use the pots somehow, I could always come up with something for the last 2 joints, even if just a home switch. I would like to use a 5i25 as it looks like I may be getting much more intimate with it in my machine project.

There really is not a lot to choose between the 5i25 and 5i23, though the 5i23 does still have a significantly more powerful FPGA.
The 7i77 offers a lot more IO on-board than does the 7i65m but I don't know how much you really need for a Puma.
You can easily connect a 7i87 to the smart-serial header of the 7i77 to add more analog inputs.

On that subject as a side note - did you (Andy) write the driver for it? .

I am not sure which "It" you mean here. But I wrote the driver for the 7i65 and the Smart Serial parts of the 7i77, so the answer is "yes" regardless.

7i65 is src/hal/drivers mesa_7i65.com and src/hal/drivers/mesa-hostmot2/bspi.c
7i77 is src/hal/drivers/mesa-hostmot2/ hostmot2.c …hm2_pci.c, …sserial.c