Linuxcnc xyz jitter when ide

Hello everyone, I'm new to linuxcnc. I testing a new setup with stepper motors and mesa7i96s, it is working fine but at idle the xyz starts jittering even after homing the axis. This cause a vibration on the stepper motors. Obviously my stepper motors don't feedback the position to Mesa controller hence I don't understand why this is happening. Attach a 3 second video to show the issue 

Grateful if you could shed some light on this.

 

typically jitter on steppers is due to electrical noise leaking in to the step/dir lines

Whilst that could be a possibility the noise would need enough strength to drive the optocoupler in most stepper drivers. Unless there is an awful lot of noise.

I think (and I maybe wrong) PID numbers can still have an affect in open loop configs, here's a brief discussion
forum.linuxcnc.org/38-general-linuxcnc-q...loop-steppers#119303

Yes, too high a P term in the local feedback loop can do this.

For Mesa hardware P should be 1/servo_thread_period
so 1000 for a  1 ms (1000000 ns) servo thread period
or 500 for a 2 ms period.