Ethercat recovery after power down

[Pauljm]

Hi Guys,

First  post here been doing lots of reading... I have been around PLC’s doing program mods and small projects as a Maintenance sparky for many years however I never really got in to the different communication protocols so I am pretty green in this area so apologies if my questions are very basic! I am currently designing a panel where I am going to use an NX1P2 and NA HMI to control a few drives etc. I only need to control and display  the speed of the drives through the hmi so its no huge deal. I have worked on a system before that was set up with many drives all daisy chained together but the problem was if one of the 3g3mx’s tripped on a critical fault, it had to be powered down completely to be reset which would then drop out the ethercat and stop all the drives after the tripped one. So if this was to happen on the system I am now designing I end up with a large fire risk. So my main question is: If there is a loss of all power for say 20 seconds, will ethercat recover and continue to control the drives? Due to the fire risk I am thinking I will control the start stop of the drives through the terminals and use either ethercat or Ethernet ip to control the speed through the hmi? Anyone got any experience with power outages and how ethercat recovers? 

Thanks for any help.

Paul

[gclshortt]

" Modular machines or tool changers require network segments or individual nodes to be connected and disconnected during operation. EtherCAT slave controllers already include the basis for this Hot Connect feature. If a neighboring station is removed, then the port is automatically closed so the rest of the network can continue to operate without interference. Very short detection times <15µs guarantee a smooth changeover"

https://www.ethercat.org/pdf/english/ETG_Brochure_EN.pdf

The above may help you out.
Regards,
Garry

[Pauljm]

Hi Garry thanks for your reply and the link. Maybe the ethercat network I used to work on wasn’t set up correctly or something but it definitely used to go down on powering down one drive. I am still in 2 minds whether to go ethercat or Ethernet for comms. What would you do?

Thanks again 

Paul 

[Michael Walsh]

Stay with EtherCAT.  You can add some "EtherCAT switches" (AKA Junction Slaves) to make your network a branching topology rather than a daisy chain topology.

Omron offers the GX-JC03 and GX-JC06 to accomplish this.

This is likely what you have:

This is what I am suggesting:

Without branching, when you power down a node in the middle of the network, all subsequent nodes lose communication.  This is not true in the branching setup, except for the nodes highlighted in yellow.  The yellow nodes will lose communications if the nodes between them and the Junction Slaves are powered off.  If you want complete immunity to this issue, connect one drive only to each of the output ports on the Junction Slaves.

 

 

[Pauljm]

Hi again and thanks for that Michael. I understand about the branching off but how about sudden power loss? Wondering if Ethercat will recover and just restart from where it was. My new panel will be backed up by another panel that has ups back up on the plc which in turn starts a generator which will  supply  back up power to to the panel with ethercat and drives. I need a couple of these drives to keep running until the oil cools down and there is no more fire risk.i guess I could put another ups to keep the ethercat healthy in this case? ( I think I just solved my problem although it’s all adding to the cost). The little din rail 24vdc  ups units from omron are pretty cool I reckon especially when power dips are pretty common due to the storms we get around here.

i still have to work out how to program the NX as I am relatively new to tag based and ethercat systems. I am sure there will be more questions.

great forum....

Thanks again,

Paul

[ex7r4n1ck]

The etherCAT will likely recover faster than the drives. The drives have to recharge their DC bus, control power, and exit their alarm state prior to being useful, whereas the etherCAT modules will get power, clear alarms, and connect on receiving power again. I am making the assumption that the same backup power goes to both pieces of equipment.

But for thorough safety/uptime, following Michael's advice and adding a UPS for the etherCAT modules would be best. The same would be true of ethernet as well.