EtherCAT Issues

[kckku 9]

We are slowly transitioning from EtherNet IP to EtherCAT so I have been reading the Omron manuals, etc. to try to learn more. The Omron manual has stated in multiple places to not randomly disconnect EtherCAT cables. Instead you are supposed to disconnect the slave using the disconnect feature in Sysmac Studio or a disconnect slave instruction tied to a button on the HMI. Is this really an issue that we need to take into consideration or is Omron just being overly cautious? What happens if I disconnect a slave and then re-connect it? Does the network recover on its own like EtherNet IP or does it require a reset/power cycle?

[Murky 0]

When you unplug a node the eCAT network will fault and stop communicating.  This will shut your equipment down.  You will need to program a eCAT network reset routine in your program to allow for the network to reset when a node is hooked back up.  The manual is correct and you probably will want the node disconnect feature added if you are going to disconnect and connect nodes.  This will allow the network to continue to operate if the node is disconnected.  Just watch your topology.  The network feeds through nodes so these will need to be at the end of a branch or on its own.

[BE 13]

I had a lot of EtherCAT issues on my last project, so played around with this a fair bit (ended up being a faulty EtherCAT hub and a fault VSD EtherCAT comms card).

I found that if a cable is unplugged, all devices downstream of that cable disconnect (obviously), but everything upstream is fine. Plugging the cable back in resulted in the network reconnecting and working as intended. That said, I did have some code in place to automatically reset EtherCAT faults as the operators usually don't check such things, and if they do, the ring me for every little error .

Without that code however, I can't recall if the EtherCAT automatically reset itself when an uplugged cable was reconnected. I can confirm that it definitely does not need a power cycle, but the error on the PLC might need to be reset/cleared (unless you code an automatic reset).

Someone else might be able to confirm if the EtherCAT network resets itself without that code.

As a side thought, the reason Omron say that could be (they might have other reasons too) is if you disconnect the slave from the network using sysmac studio or a button, no EtherCAT errors will be raised on the PLC. Basically, the device is still in the code and shown in the network topology, but the PLC no longer "looks for it" so to speak. I had to do this for one of my VSD's while waiting for a new comms card to arrive. However, my VSD was at the end of the network topology, and I don't know how downstream devices are handled if an upstream device is disconnected through Sysmac Studio (assuming the cables remain connected and the device is powered on).