dmesg | grep EtherCAT
[    9.817042] EtherCAT: Master driver 1.6.8 1.6.8.g2543cc5-1+27.2
[    9.818563] EtherCAT: 2 masters waiting for devices.
[    9.847342] ec_generic: EtherCAT master generic Ethernet device module 1.6.8 1.6.8.g2543cc5-1+27.2
[    9.847367] EtherCAT: Accepting 00:18:7D:08:B9:20 as main device for master 0.
[    9.866172] EtherCAT 0: Starting EtherCAT-IDLE thread.
[    9.866836] EtherCAT: Accepting 00:18:7D:08:B9:21 as main device for master 1.
[    9.877977] EtherCAT 1: Starting EtherCAT-IDLE thread.
[   12.321933] EtherCAT 1: Link state of ecm1 changed to UP.
[   12.330220] EtherCAT 1: 8 slave(s) responding on main device. Re-scanning on next possibility.
[   12.330224] EtherCAT 1: Slave states on main device: INIT.
[   12.330226] EtherCAT 1: Re-scanning now.
[   12.331249] EtherCAT 1: Scanning bus.
[   12.337915] EtherCAT 0: Link state of ecm0 changed to UP.
[   12.349920] EtherCAT 0: 4 slave(s) responding on main device. Re-scanning on next possibility.
[   12.349923] EtherCAT 0: Slave states on main device: INIT.
[   12.349924] EtherCAT 0: Re-scanning now.
[   12.350438] EtherCAT 0: Scanning bus.
[   13.362817] EtherCAT 1: Bus scanning completed in 1032 ms.
[   13.362823] EtherCAT 1: Using slave 0 as DC reference clock.
[   13.362825] EtherCAT ERROR 1: Failed to calculate bus topology.
[   13.445923] EtherCAT 1: Slave states on main device: PREOP.
[   13.973808] EtherCAT 0: Bus scanning completed in 1620 ms.
[   13.973813] EtherCAT 0: Using slave 0 as DC reference clock.
[   13.977919] EtherCAT 0: Slave states on main device: PREOP.