[etherlab-users] Configuring DC for a axis control

Ezio DelBono edelbono at electroengineering.it
Fri Jan 28 09:19:22 CET 2011

Hello all,
I am using the ethercat master version 1.5 to control some brushless 
motor drives with Dc support.
What my application does, is to read every 1ms the actual position 
(0x6064) and send the target velocity (0x60ff) to the drive and read the 
status word and write the control word as well.

My application is executed by RTAI-Lxrt in user space with a period of 
1ms and a jitter of 200us (due to the character device). I am quite sure 
that the dc is running well because I monitor the SYNC0 generated by the 
first slave that is the reference clock.

Anyway I haven't understood how I have to configure the 'shift time' in 
my application because the problem is:
Sometime (every 2-3 seconds) the actual position is not refreshed 
meaning that I read the same actual position in the next cycle. This 
occurs when my application period has the worst jitter. How can I set 
the shift time to compensate it? Or this is not the right solution?

Kind regard,
Ezio DelBono

More information about the Etherlab-users mailing list