Converting a Linear topology to a ring network. Will it work?

clegger

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Jan 2017
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Hi, I have been doing quite a bit of research on ethernet/IP and believe my idea will work but I'd like to get some second opinions. We have about 30 powerflex 70 drives with 20-Comm-er cards in them all Daisy chained creating a linear network. The first drive is connected to an unmanaged switch which has 4 additional drives connected to it separately. The switch is connected directly to the enbt card in our chassis. The last drive in my linear network is not connected to anything expect the drive before it. Everything works A-Okay until we need to turn one drive off. Everything downstream loses communications and the whole machine stops. I know this and try to use the local motor disconnect but somehow some of the older guys in our plant can't seem to get this.

So, doing research, I have come up with an idea.
-gettinf a 1783-ETAP and connecting the first drive to port 1 and the last drive to port 2 and then plugging port 3 into my unmanaged Ethernet switch. I will set the ETAP as the ring supervisor. I believe my ring will work but will it work how I want it by going through a switch?

Also, do the 20-Comm-er cards automatically detect a ring network or is there configuring that needs to be done?

I'm attaching some pictures of this clusterfu*k we've got going on. The 30 drives in a row is what I'm wanting to convert to ring. And the other larger drives are the others connecting to unmanaged Ethernet switch. And the chassis is where they are communicating to.

Any help would be appreciated!

Thanks!

IMG_1924.jpg IMG_1925.jpg IMG_1927.jpg IMG_1928.jpg
 
From EtherNet/IP Embedded Switch Technology manual:

Connect switches to a DLR network via 1783-ETAP, 1783-ETAP1F, or 1783-ETAP2F taps.

If switches are connected to the DLR network without the use of a 1783-ETAP, 1783-ETAP1F, or 1783-ETAP2F tap, the network can experience unpredictable behavior and network performance is unknown.

Configure multiple supervisor nodes per ring.

If your DLR network has one supervisor only, and the supervisor experiences a fault, none of the other nodes become the active supervisor. In this case, the network becomes a linear network until the fault is corrected and the DLR network
restored.

Another reason to configure multiple supervisor nodes is that if you need to replace an active supervisor node with an out-of-box replacement, the new device is not enabled as a supervisor (by default) and there is no supervisor on the
network.
I'd add an EN2TR to the chassis (previously checking the compatibility with the actual controller). The ring would be something like:

Code:
+-- EN2TR --- VFD#1 --- ....... --- VFD#30 ---+
|                                             |
+--- ETAP ------------------------------------+
       |
     SWITCH -> other VFDs
 
From EtherNet/IP Embedded Switch Technology manual:

I'd add an EN2TR to the chassis (previously checking the compatibility with the actual controller). The ring would be something like:

Code:
+-- EN2TR --- VFD#1 --- ....... --- VFD#30 ---+
|                                             |
+--- ETAP ------------------------------------+
       |
     SWITCH -> other VFDs

But will it work like this? I've read that the en2tr doesn't have to be the supervisor. I can also get an etap easier than and en2tr
 
You can just use an ETAP. You can designate any of the DLR device to be the supervisor from RSLinx including an ETAP.

eta: what is the exact part # of your comm 20 card?

eta2: it's way way better to get EN2TR though. Going through an ETAP then a unmanaged switch to your most critical device, the PLC, kinda defeat the purpose of the DLR. I would replace the ENBT with EN2TR then also get an ETAP for the switch. I'm assuming the 4 stand-alone VFD doesn't have DLR capability?
 
Last edited:
You can just use an ETAP. You can designate any of the DLR device to be the supervisor from RSLinx including an ETAP.

eta: what is the exact part # of your comm 20 card?

Okay, yay! I was hoping that would work!
And It's a 20-Comm-ER I'll have to look when I get to work tonight for the exact part number. But I did read that it supports DLR.
 
You can just use an ETAP. You can designate any of the DLR device to be the supervisor from RSLinx including an ETAP.

eta: what is the exact part # of your comm 20 card?

eta2: it's way way better to get EN2TR though. Going through an ETAP then a unmanaged switch to your most critical device, the PLC, kinda defeat the purpose of the DLR. I would replace the ENBT with EN2TR then also get an ETAP for the switch. I'm assuming the 4 stand-alone VFD doesn't have DLR capability?

I guess just 20-COMM-ER

IMG_1935.jpg
 
eta2: it's way way better to get EN2TR though. Going through an ETAP then a unmanaged switch to your most critical device, the PLC, kinda defeat the purpose of the DLR. I would replace the ENBT with EN2TR then also get an ETAP for the switch. I'm assuming the 4 stand-alone VFD doesn't have DLR capability?

I agree with it being way better to get an EN2TR but, if possible, I would not remove the ENBT. If you have an extra slot in the chassis, put in the EN2TR and leave the ENBT. The ENBT can go to the switch and then you connect the ring to the EN2TR. If there is no free slots in the chassis then I would put in the EN2TR, remove the ENBT and use an ETAP to go to the switch.
 
I agree with it being way better to get an EN2TR but, if possible, I would not remove the ENBT. If you have an extra slot in the chassis, put in the EN2TR and leave the ENBT. The ENBT can go to the switch and then you connect the ring to the EN2TR. If there is no free slots in the chassis then I would put in the EN2TR, remove the ENBT and use an ETAP to go to the switch.

What are the reasons why? Why wouldn't you do it how I am wanting to do it?
 
You can just use an ETAP. You can designate any of the DLR device to be the supervisor from RSLinx including an ETAP.

eta: what is the exact part # of your comm 20 card?

eta2: it's way way better to get EN2TR though. Going through an ETAP then a unmanaged switch to your most critical device, the PLC, kinda defeat the purpose of the DLR. I would replace the ENBT with EN2TR then also get an ETAP for the switch. I'm assuming the 4 stand-alone VFD doesn't have DLR capability?

I don't know how I missed the second part of this question, whoops.
We could probably convert the 3 other power flex drives over to 20-Comm-ER cards but the other 2 drives do not support DLR. And I'm only wanting the DLR because we are often having to shut this entire machine down just to turn off one of the drives because everything down stream from the drive we turn off quits communicating. If we didn't have to have a massive number of switches we could just put all of the drives on a star configuration and problem would be solved.
 
I don't know how I missed the second part of this question, whoops.
We could probably convert the 3 other power flex drives over to 20-Comm-ER cards but the other 2 drives do not support DLR. And I'm only wanting the DLR because we are often having to shut this entire machine down just to turn off one of the drives because everything down stream from the drive we turn off quits communicating. If we didn't have to have a massive number of switches we could just put all of the drives on a star configuration and problem would be solved.

I'm very curious, given your pictures how can you even shut one drive down without shutting the whole thing off from simply a safety perspective? I feel like you need a 40 cal suit just to be in that room.

Even with a ring, what happens if you need to shut down 2? Same problem unless you run a patch cords to bypass the ones you need to shut down. You can get creative an put an etap at each drive, the etaps stay in the DLR ring then you can shut drives off as needed. But thats really costly.

You can get 24/48 port switches and put them into a standing or wall-mount rack then patch them over. So maybe 1 - 2 switches in this case? The bigger issues is cabling.

You can complete the ring easily, and if you don't have devices that are DLR compatible just add additional etaps as required. My guess is a star topology is what you really need and probably best to invest in.
 
You may want to consider sectioning off the drives too. Put 4-6 on one ETAP and create a small DLR network section, repeat. Then run your 4-8 Etaps you end up with back to a small switch.

It's a compromise if money is an issue, but should give you more flexibility.
 
I'm very curious, given your pictures how can you even shut one drive down without shutting the whole thing off from simply a safety perspective? I feel like you need a 40 cal suit just to be in that room.

For real! When I started working here I was like... Does this even meet safety regularuins.

But okay. I will discuss the options with my guys and see what we can come up with. And normally when we are turning a drive off its to a portable conveyor or when were changing a belt on a conveyor or something were fixing to get lockable disconnects for the power feeding these drives and these are going to be our lockout points. Normally we just remove the drive from the Ethernet circuit were going to be turning off and keep everything else online but still. Creating a ring network would just reduce the downtime by 10 mins or so.

Thanks for y'alls help!
 
I would go with (2) 24 port switches or (1) 48 port switch as suggested. That's what you really need. You could run the new Ethernet cables one at a time as time allows to make it more manageable.
 
What are the reasons why? Why wouldn't you do it how I am wanting to do it?

The reason, as mentioned above is that if you leave the ENBT and put in a single E-Tap then one specific cable and you lose all the drives, I always feel its better to put the PLC into the ring.

As for why I´m suggesting continuing using the ENBT aswell as the EN2TR is in terms of cost. If you decide to put in a EN2TR then you need something that can give you a branch to go to the switch. Since you already have an ENBT you would not need to buy an E-TAP.

Regards
Ian
 

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