EtherCat Sync & DC problem

Hi Sirop,

i have tried sycn0shoft value as per link send by you...but no change in result...

Also i have tried compiling with "3.4-9-rtai-686-pae" code from link below...but its gives warning of "UNKOWN SYNBOL __moddi3"...i have tried resolving this issue but no luck on that side... any one have any idea about this error??

github.com/sittner/linuxcnc-ethercat/tree/fix-dc-sync

Are you trying to run Linuxcnc within a virtual machine?
You should know that real time kernels don't work in VMs. Latencies will be all over the place and unusable. They have to run on bare hardware in order to get usable latency. A VM is fine for some testing and development, but anything timing dependent can't be expected to work.

Automata27 wrote: Hi Sirop,
Also i have tried compiling with "3.4-9-rtai-686-pae" code from link below...but its gives warning of "UNKOWN SYNBOL __moddi3"...i have tried resolving this issue but no luck on that side... any one have any idea about this error??

github.com/sittner/linuxcnc-ethercat/tree/fix-dc-sync

This new feature would only work with RT_PRREMPT, see github.com/sittner/linuxcnc-ethercat/iss...suecomment-371898365

Hi Todd Zuercher,

no i am not running linuxcnc in VM...i am running in mother board with atom quad core processor and 4gb ram...

Automata27 wrote: as per your suggestion following settings i have changed...

refClockSyncCycles = "* 1" and sync0Cycle = "configured cycle time"
sync0Cycle = "1000000"
sync0Shift = "0"

attached is the waveform that i got now...still dc issue is there...

i am configured drive DC synch mode...
cycle time that i use is 1ms....

as per your suggestion if i set sycn0shift = "half cycle " then also same issue...no change...

hello Automata,
I'm sorry I could not help you.
regards
Chimeno

Automata27 we also have some DC syncs problem.

I copy you some links:

lists.etherlab.org/pipermail/etherlab-users/2018/003281.html
github.com/sittner/linuxcnc-ethercat/issues/45

Sascha is improving the sync function and he is trying to achieve the B method described by Graeme Foot here
lists.etherlab.org/pipermail/etherlab-users/2016/003013.html

You could try to install rt-preemt and try the fix-dc-sync version that sascha has programmed. The desync problems in ciclyc position mode continues for me using it but you could try it. More feedback could help him.

I think the origin of the problem is the time between sent packets. If you try to use wireshark like I described in github issue you could investigate it deeply.

BR
Nacho Rosales