Actual position and Commanded position differ, using cia402 [SOLVED]

I see you have a userkins module, that one becomes suspicious of course.

I agree, this is most likely a problem with your custom kinematic module. I usually see these kinds of jumps when the forward and the inverse kinematics do not match up.

I checked the userkins.comp file, found nothing strange, but in userkins.c, it was

int kinematicsForward ...
   ...
    pos->tran.x = j[0]/80; // X coordinate
    pos->tran.y = j[1]/80; // Y coordinate
    pos->tran.z = j[2]/80; // Z coordinate

while in userkins.comp or either of the kinematicsInverse functions, the /80 was not there. I tried compiling again, nothing changed. I tried deleting the /80 from userkins.c, everything is now working. I just have no idea why..

Could be, but I can't figure out where it's coming from, so looks like I'm stuck with a temporary fix of a possible temporary fix for now.

I remember Python giving me so much grief over the tabs and spaces in my first year of learning to program! At least these days IDEs take care of that problem.

C just went completely over my head when I tried to learn it. I can mostly read it but I cannot write anything in C, it's pretty frustrating

Sounds like a problem compiling the .comp file as the 'halcompile' tool would not add or remove anything in those lines.
Impossible to say without actually seeing your userkins.comp file.

Oh thanks! you're right that halcompile is having some problem, userkins.c is unchanged after I run . There's nothing in the terminal that hints at it not working.

Compiling realtime userkins.c
Linking userkins.so
cp userkins.so /usr/lib/linuxcnc/modules/

I've attached the userkins.comp file here

I think you are being confused by an old version of 'userkins.c'. Note that

will not create a 'userkins.c' file at all, it will directly create a 'userkins.so' and copy that to the appropriate folder.

linuxcnc.org/docs/html/man/man1/halcompile.1.html

If things are working after
'sudo halcompile --install userkins.comp'
then you can delete the 'userkins.c' file.