Hi,

I'm testing out the electronics setup for a new machine i'm building. Currently i'm testing the axis electronics. I have my servo-drives attached to the drivers, and the drivers connected together via ethercat. This is then connected to a Beckhoff module and then on to my control pc(LinuxCNC) via EtherCAT. I've used short cat 6A S/FTP cables for best possible shielding of the ethercat bus. I've grounded the drivers, the beckhoff modules and the computer via 2,5mm2 cable which again is grounded via the wallsocket. All components are layout out along the table, with about 2m from the motors to the drivers, about 5-10cm between the drivers, about 1,5m from the drivers to the Beckhoff modules and another 1m to the computer. However, when the drivers "kick in"("Voltage enabled" via the controller) the entire EtherCAT bus gets scrambled and loses connection for a couple of seconds, here is a screenshot of the bus just before and just after the drivers gets enabled:
Attachment 460822
(1st: all is ready for enabling drivers, 2nd: just after voltage-enable, all devices are lost, 3rd: after a couple of seconds, "something" is found again)

The drivers are 3-phase 2,2kW CTB-brand and my guess is that the voltage-enable causes a small EMP which causes the problems. If i only run 1 driver there is no issues...2 drivers works most of the time...3 never works... and i actually have a 4th 7,5kW driver for spindle i haven't even connected yet :-/ It doesn't matter which drivers that i put onto the bus(i thought maybe one was bad, but they all act the same)...

This is going to give me a headache if i can't even power it up on the table...then it will never work when i put everything into a box :-/

So questions:
- How does large VMC's handle this? Do they stage the "voltage enable" so not all drivers turn on at the same time?
- Are drivers seperated in the larger setup's by shields or something?
- Any ideas to what i might try or what i have missed?

Any input will be greatly appreciated!

/Thomas