7I90HD with Raspberry pi and getting weird joint 0 following errors

PCW wrote:

A couple of things:

With a 0.050 mm maximum following error, 250 usec of servo thread jitter will cause a
following error with your current setup . What is you servo thread jitter?

There are a couple of things that can be done to improve stepgen performance with regard to host jitter:

1. Use the stepgen in velocity mode and a PID loop to control the position (use a pncconf created hal/ini file set as a model)

2. Use the DPLL to reduce host servo thread jitter impact on position sampling errors

can i make a pid loop in an openloop configuratuion? i thought i need an encoder for that.

Yes, take a look at a pncconf created step/dir hal file.

i made a config with the pncconf that works

there are two things

1. im not sure if the shared home switch for x & x2 are correct set
2. ferror seems to be a bit high

what do you think?

You should be able to set the ferror and min ferror much smaller
also all lines like: setp pid.?.maxerror .0005 should be commented out

You can further improve the following error by using the DPLL:
# latch stepgen position feedback 100 usec before nominal read time:
setp hm2_[HOSTMOT2](BOARD).0.dpll.01.timer-us -100
setp hm2_[HOSTMOT2](BOARD).0.stepgen.timer-number 1