delay when syncing axis with MC_GearInPos

[bschmidt]

This may be related. When I synchronize a real axis to another real axis using MC_GearInPos and SyncSource =  SYNC_ACTUAL, the slave lags the master by 12 ms (6 EtherCAT cycles). If I switch to SyncSource = SYNC_ACTUAL_EXTRAPOLATED, the lag is resolved (but also the feedback noise is amplified). Why are so many cycles lost and need to be compesated for? 

SYNC_ACTUAL

SYNC_ACTUAL_EXTRAPOLATED

[CodeShepherd]

Moved to own topic from "Subject: Why is there a five-cycle delay in motion?".

[NormalOne · Accepted solution]

Hello,
the delay is the result of the following reasons (In the CML-System there was a delay of 4 cycles):
+ Fineinterpolation in the drive according to Parameter P-0-0187 (default values => 2 cycles) 
+ Transmission of command value and receiving of actual value (1 + 1 cycle)
+ actual values are transfered to axisprofile/distribution after Motion (1 cycle)
+ command values are not directly transfered to the drive (1 cycle)
This is independent of the operation mode (also in position mode and so on). To be synchron this must be compensated. 

[bschmidt]

Hello,

Thank you for the explanation.

Best regards,

Brian