ENBT card

[Automationplcman78]

Hi,
we are using ENBT cards to communicate to our PLCs in different sites, the problem is that in one site everytime we need to reset some of those cards(Recycle the power for the card then will work ok), seems like data traffic problem.
NOTE: in that site we are using Radio Link, I mean 12 PLCs connected to a switch by ENBTs then to Radio Link to our network.

Is some one has any solution for this problem, instead to go everytime to reset those cards?

Regards

 

[DixieM]

This may be a bit from the left playing field, but if one can use a cell phone to detonate an explosive device, surely one can use a cell phone to reset a bank of ENBT cards?

 

[The Plc Kid]

Always best to have 2 links or paths to remote sites primary and backup and the backup to be able to pwercycle thing if need be. Most people use a cell modem to do this as not much comms traffic is needed to send a reset command.

You say 12 plc's on one switch? I assume then they are all on the same network using Ethernet IP sound like you may have a traffic issue / flooding. Are you using multicast or unicast> what major firmware revs are the plcs running?

Are the plc's just talking back to you main site or to each other also?

what amount of traffic are you pulling back to your main site and how fast are you polling it?

 

[Automationplcman78]

Note

Thanks for your reply,

To make it clear,
we have 12 ControlLogix, in different chassis, and each chassis has two ENBT card (1756-ENBT A), first card is used direct to HMI in the same panel. The second card is connected to Fiber converter (Ethernet to Fiber), then to Fiber switch to Radio Link(Microwave) to Server in Control room.

1st panel:ControlLogix -> EtherNet2Fiber Converter TO
2nd panel: ControlLogix -> EtherNet2Fiber Converter TO
.
.
.
.
.
12 Panel: ControlLogix -> EtherNet2Fiber Converter TO


TO Fiber Switch, To radioLink(Microwav), To ControlRoom.


That exactly what we have in that site, other sites we don’t have problem as we connected 12 ControlLogix direct to control room by FiberOptiic.
Only the site that has RadioLink we face a problem with ENBT cards, between time and time we need to go to recycle the power of that card.

Any Idea?


Regards,
Alsaaidi

 

[The Plc Kid]

Is each rack / Card a seperate network or all one network to the radio link?

How much data passing on the combined network or each network?

Are you using multicast or not? Depend largely on the controller and enbt firmware.

Is your fiber switch managed or unmanaged? Does it have IGNP snooping and Querier? Is it enabled?


I am thinking you are drowning your radiolink in excess traffic due to multicast packets as well as locking up your enbt cards in the process.

We need answers to the above questions to be sure, just guessing now.

 

[Automationplcman78]

Is each rack / Card a seperate network or all one network to the radio link?
All in one Network

How much data passing on the combined network or each network?
I don’t have any Idea about it

Are you using multicast or not? Depend largely on the controller and enbt firmware.
Multicast
Is your fiber switch managed or unmanaged? Does it have IGNP snooping and Querier? Is it enabled?

It is Unmanaged.

I am thinking you are drowning your radiolink in excess traffic due to multicast packets as well as locking up your enbt cards in the process.
Do you mean too much data is transferred to Enbt card from radio link

Another thing, what is the Maximum data that 1756-ENBT/A card can work on ?
Is there any new card which can work on higher data rate, and is there any data base logger or any software that can help to save the event/change on that card then easly we can know what was the last maximum data rate that our card reach.


Best regards,

alsaaidi

 

[The Plc Kid]

If you have 1 network with 12 enbt cards to a unmanaged switch using multicast then that is most likely your problem.

Not sure of the the amount of throughput on a enbt you will need to check the ab website for that info.

Are the controllers swapping data with each other or just with the central station?.The enbt cards are good for 250 connections so I doubt you are hitting that limit.

You may want to look at the latest rev of firmware for those enbt cards versus what you have. For simplicity I would make them all the same. Check the hard ware revisions also to see if there are any differences.

Wireshark would be a good tool tom setup and good a good picture of what is going on.

My money is on the multicast and unmanaged switch though. A managed switch with IGMP snooping turned on would likely solve your problem.

 

[dmargineau]

1756-EN2T will be the highest end of the CLX EtherNet/IP bridges product family-128 TCP/IP allowable connections vs. 64 for the ENBT, theoretically twice the throughput; $2787 vs. $2090 list.
Have you used the existing bridges' built in web interfaces when troubleshooting? They are very handy and offer a lot of relevant information about the network's health.
Most of the time, before deploying any "sniffer" software, you could at least get the big picture.

 

[Ken Roach]

Plcman78, I think you have a good idea of the "things you don't know" that need to be investigated.

In my experience, unmanaged switches plus radio links always adds up to poor performance, even without the added complication of multicast traffic.

The absolute first step you should take is to set up some kind of monitor on the radio link to find out how much traffic it is carrying. The second step is to determine if that traffic needs to cross the radio link or if it should be filtered to stay on one side.

If the radio itself has this sort of feature, or if you need to learn about Ethernet taps and port mirroring are things you will have to investigate.

My guess is actually opposite from PLCKid's: I think that the 1756-ENBT modules probably have plenty of bandwidth, but are running out of logical TCP Connections because connections are being abandoned due to packet loss faster than they can be canceled by timeouts.

 

[The Plc Kid]

PLCman78

Heed Ken's advice. I posted 250 connections for enbt's but that is incorrect dmargineau has given you the correct info there and as ken said it is most likely that you do not have enough connections to compensate for this excess traffic you have.

Solution in my mind would be to increase connections and eliminate unnecessary traffic such as unfiltered multicast traffic and add a managed switch.

IMO the managed switch may give the best bang for your buck as a first step.

Just for your info the 250 connections I posed by mistake is the max a contrologix controller can handle with the exception of the new L7X series which does 500 connections per processor.

 

[Automationplcman78]

Thanks

Thank you guys for your information.
I'm going to talk with Telecom department regarding the manage switch with IGNP snooping.
you guys are right, we need to monitor the radio link traffic and filter unnecessary traffic.

NOTE: I attached the TCP statistics of one of our ENBT card

Thank you all for the good information