Spindle Step/Dir servo ramp down before stop on M stop command.

That is true. I am trying to see if I can modify the mesa stepgen.c to turn the C to 360 position before resetting.
Also, in stepgen.c, I am working to wait before executing the position-reset action.

Is it possible to use any programming statements in these M101 files.
Like Do loops or if statements. ?

andypugh wrote:

RBC wrote: halcmd setp hm2_7i92.0.stepgen.04.position-reset 1

This is the easy way to prevent a large error on switchover, but it has the disadvantage of not giving a repeatable zero for the C axis.

This can be avoided by using an index input and stepgen index

If LinuxCNCs motion comp could be asked to rehome a joint including
the part where it forces its commanded joint position to equal the current
joint feedback position, this would be easier.

Indexing:
It seems to me that this indexing can be done in the Mesa firmware. This way we wont have to add a hardware encoder/indexer to the motor. In my case, I am using a teknic servo, and it does not/cannot miss a step, and does not have available encoder outputs. The only output it has is the fault output, which I connected to a fault input of the joint. It aborts if motor goes above its limits.

Following Errors on switch over:
Somehow, I need to add a loop to wait until joint speed is 0 and execute the position-reset. Adding arbitrary delays here and there works for some cases, and does not work for others.
I have tried this using a M201 in remap.py without much success.

If you are not using a physical index, no firmware support is needed
you would just make a simulated index component in hal

I tried to add similar functionality in stepgen.c. It was not able to update fast enough to be useful.
I will look into creating a hal component.