[etherlab-users] Questions about DC

[Gianluca Medini]

Good morning, I'm using the Igh ethercat master to play motor drives 
with DC.
What I see is a time to have a little difference in timing (registser 
0x92c) that is very long (the first time I start the master is about 30 
seconds, if I restart also much more).
Inspecting the 0x92c seems we have oscilation that need   a long time to 
end.
I don't know if this is normal since I've no experience with other masters.
However I've seen an asimmetry in code for user and hard real time.
1) In user example
         // write application time to master
         clock_gettime(CLOCK_TO_USE, &time);
         ecrt_master_application_time(master, TIMESPEC2NS(time));

2) In rtai example.
....
      tv.tv_usec += 1000;
         if (tv.tv_usec >= 1000000)  {
             tv.tv_usec -= 1000000;
             tv.tv_sec++;
         }
         ecrt_master_application_time(master, EC_TIMEVAL2NANO(tv));

   In the RTai example the clock is taken a first time before the main 
loop and after is calculated manually (incrementing 1000 mSec), in these 
way (it seems to me) the time I give to master is always with the (small 
enough) jitter of the RTai scheduler.

I'm wrong ?


-- 
Dott. Gianluca Medini
Eurosoft S.r.l.
Viale Colombo 74
Fucecchio FI

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