I am using Scara3 kinematic with EtherCAT PLC. The robot stops at the same place randomly after few cycles.
Check attached image. I am getting SMC_ERROR.SMC_DI_FIELDBUS_LOST_SYNCRONICITY in all 3 axes.
Thanks Georg for responding.
I have followed the suggestion mentioned in the real time problem.
However, it does not solve the problem.
The weird part is, the robot stops at the same position randomly and it does not stop when I increase the speed of the motion.
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Here I have attached the task monitor data.
What is very weird is that I am using MC__MoveDirectAbsolute FB, when I choose Vel/ACC/Jerk Factor to 1.0 it run fine. It ran 10 hours without the issue. But I get the error randomly when I use factor as 0.5
the maximum cycle time of the EtherCAT_Task is very high, ca. 35 ms. Could you please check if this is just the first cycle after starting the application or if it happens during motion? (You can reset the times in the task configuration by right-clicking in the "monitoring" tab.)
Another thing to try: put the SoftMotion_Planning task on a different core.
Best regards,
Georg
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I am using Scara3 kinematic with EtherCAT PLC. The robot stops at the same place randomly after few cycles.
Check attached image. I am getting SMC_ERROR.SMC_DI_FIELDBUS_LOST_SYNCRONICITY in all 3 axes.
Hi aniket-b,
this error has nothing to do with the scara3 kinematics, or robotics, or SoftMotion.
It means that the EtherCAT bus is not synchronized. The usual cause is that the realtime of the PLC is not sufficient.
See https://content.helpme-codesys.com/en/CODESYS%20SoftMotion/_sm_basic_common_errors.html for details and ways to solve the problem.
You can also check the PLC log for additional information about the error.
Best regards,
Georg
Last edit: gseidel 2025-12-23
Thanks Georg for responding.
I have followed the suggestion mentioned in the real time problem.
However, it does not solve the problem.
The weird part is, the robot stops at the same position randomly and it does not stop when I increase the speed of the motion.
hi,
which plc are you using?
is it realtime capable? Linux with preempt rt or Control RTE on Windows?
It is Moons PLC which uses Codesys IDE.
https://www.moonsindustries.com/series/mca6-medium-motion-plc-a150102
This has Realtime capability using Linux with preempt
Last edit: aniket-b 2025-12-29
Please check the jitter in the online taskmonitoring.
cylce time of the motion task and jitter in case of the error.
Here I have attached the task monitor data.
What is very weird is that I am using MC__MoveDirectAbsolute FB, when I choose Vel/ACC/Jerk Factor to 1.0 it run fine. It ran 10 hours without the issue. But I get the error randomly when I use factor as 0.5
@eschwellinger any suggestions here?
Hi aniket-b,
the maximum cycle time of the EtherCAT_Task is very high, ca. 35 ms. Could you please check if this is just the first cycle after starting the application or if it happens during motion? (You can reset the times in the task configuration by right-clicking in the "monitoring" tab.)
Another thing to try: put the SoftMotion_Planning task on a different core.
Best regards,
Georg
Last edit: gseidel 2 days ago