C Axis question

Hello All.

I have 4tx axis (C axis), i need run him in continuous rotation as lathe.
i created 2nd spindle an coonect him stepgen.command-vel
ok just fine.
When i try switch back to C axis, linuxcnc trying move to back position (joint.5.pos-cmd) and i got following error.
 
What's a correct way ?


p.s. i use a mesa card. 

Look at the "orient" HAL component as a way to subtract complete turns from the commanded position.

thank you, I need full working 4 axis a turn\mill lathe.
I try to use switch kinematics.