Hello Ezio,
Depends a little bit on the slave.
I know Beckhoff AX-systems. there you must have a latency <=2%. So I
think your system is not the right way to do it.
If you have a bad sync behavior you will have no chance to compensate
this by other parameter.
Greatings
Andreas
Am 28.01.2011 11:04, schrieb Ezio DelBono:
Dear Andreas,
I know that. In fact in the past i tried to write some wrapping
functions to avoid ioctl system call but now I'm wondering if the
jitter is still acceptable without doing any hack to the master.
How much should be the maximum and minimum latency of the ethercat
frame so that the DC mechanism can work properly?
Must be the 10% of the period time? In my case I have the 20%.
Can I compensate it optimizing the "shift time"? My idea is to bring
the frame arrival in between two Sync0.
Does it make sense?
Thank you very much,
Ezio
On 28/01/2011 09:51, Andreas Stewering-Bone wrote:
Hello Ezio,
Are you really sure, you use the master under lxrt with realtime
capabilities.
There is no lxrt or rtdm interface for the master until now.
Greatings
Andreas
Am 28.01.2011 09:19, schrieb Ezio DelBono:
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
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