Handle different drives with different cycle times?

[ericvergara]

Hello,

We would like to run some axes to the standard 2 ms Ethercat time and the others to a higher cycle time for example 4 or 6 ms as we intend to free load of the cpu,

Is this possible with the actual ctrlX Core? If so, how can we do that?

Many thanks,

[CodeShepherd]

As in a ctrlX CORE X3 there is only one EtherCatMaster with a single update rate it is not possible to have slaves with different update rates. But the EtherCat should not utilize much CPU load.

Having different PLC tasks with different task cycles for axes commanding will have a way greater effect.

With the high performance ctrlX CORE X7 it is planned to have more then one EtherCatMaster so it will be possible for this hardware.

[ericvergara]

Hello CodeSheperd,

Thank you for your fast answer, another question regarding this topic,

What if I want to command the axes with Softmotion / Motion? The motion task (that is the Ethercat Cycle Time) could run at 2 / 4 / 6 ms,

Can I command axes at the cycle time of the motion task and the other axes with another cycle time?

Thanks, 

[CodeShepherd · Accepted solution]

Like mentioned above, commanding of axes is always possible, independently of the cycle time of the fieldbus, e.g. via the PLC in different tasks and cycle times. So it doesn't matter if ctrlX MOTION or Codesys Softmotion is used. The update rate of the EtherCat and so the cyclic position command value would still be sent each 2ms.

As an example:

1. You have two tasks one running in 10ms and one in 4ms. You use the first one to check position and command some axes and the same in the second for other axes. Then the commands are added to the ctrlX Motion in 10ms/4ms but the interpolator will run in 2ms to be able to send each bus cycle a new position to the drive.
2. Same for Codesys softmotion but if its interpolator is running in the first task, the drive will get five times the same position command as the fieldbus is still running in 2ms. Further more the softstack could/will utilize more CPU load the ctrlX MOTION does.

[ericvergara]

Thanks CodeSheperd,

Super clear!