Ethernet Machine Network

[clegger]

I am working on a little project at work converting a feed conveyor from relay logic to PLC. Engineering dept took this project on but didn't quite do what we wanted so I am trying to retrofit it. There is a compact logix processor, a Point I/O via ethernet and 4 power flex 525 drives via ethernet on this feed conveyor. I have an existing Control logix processor acting as a bridge from my plant network to this machine network. I have another compact logix, 2 PLC5's, 5 drives, and 3 panel views on this network already. I wanted to run ethernet from the existing machine network over to my switch so that i could go through the bridge thats already in place and get to my stuff remotely without being there at it plugged in. I have to go through engineering to get ethernet run in my plant because of contracts and they won't let me. They said i will have to go directly to the plant network because it will overload the existing machine network. I just do not believe this. Im unable to get an explanation from them on why this won't work other than him saying they are on a different subnet mask. Okay, well I can change my IP's and all that to make it work and they still say no. What am I missing here?

Thanks!

 

[JohnCalderwood]

First thing I would do is to draw out a network block diagram showing what you have on the various networks, with all the devices and their expected IP addresses.
Detail what is communicating with what, what devices are being controlled by what processor, then what you are trying to achieve.

Reading through your post, I can make assumptions of what I think you mean, but to me, it is not 100% clear what you have and what you are getting to, never mind the differences that you have between plant network, machine network, and how your role differs from "engineering dept".

 

[Timbert]

Without knowing a lot more details like the number I/O and update rates we can't really answer the question. My gut reaction is that it shouldn't be a problem considering its just running a conveyor and not some high-speed, high-accuracy multi-axis robot.

Allen-Bradley has a free Ethernet IP network estimation tool. Put the details in there and you will at least have some real numbers to show.

Philosophically, I think I agree with the 'engineering department.' In that, each machine should be hooked to the plant network and not hooked to another machine's network.

 

[rdrast]

Save yourself (or someone else) future pain.

Each and every "Machine" should hook to an enterprise network at only one point.

I usually go farther, and isolate out the IO/Drives to one absolutely local private subnet (192.168.x.y) and have a separate network connection to the plant machine network.

 

[clegger]

Save yourself (or someone else) future pain.

Each and every "Machine" should hook to an enterprise network at only one point.

I usually go farther, and isolate out the IO/Drives to one absolutely local private subnet (192.168.x.y) and have a separate network connection to the plant machine network.

I agree, which is why I want to hook this section of this machine to the same network as the rest of this machone, but I'm getting told it will "over load the existing network"

The only reasoning I can come up with is because this feed conveyor has 1 network and it's not possible to add another network card to the compact logix controller. So when I plug the existing network into my feeder Ethernet switch all 4 drives, plc, and point I/0 then get dumped on the whole machine network.

Could I use a NAT device to separate them here? Plug the machine network into the nat and just allow the PLCs address to be sent out into the machine network?

I will try to draw out a network map for y'all soon.

 

[GTUnit]

IT department wonks are usually clueless when it comes to Industrial Networking.
Adding these devices will definitively not overload the capacity of that particular Ethernet segment.

There is a physical distance limitation of 100m on Ethernet runs.
Processors and Network cards have limitations on how many connections they can support but you wont have an issue considering you are using Controllogix as the bridge.

 

[clegger]

Okay guys, here is my network for a particular machine,

Green is ethernet lines i am wanting to run.
Red is existing ethernet lines
Blue is showing where stuff is being sent and received to drives
Yellow is showing what PLCS Communicate.

Let me know what y'all think and sorry its like s 2 year old did it.

 

[Helliana]

This question is a lot more involved than if an X number drives, Y number of Controllers, and Z number of Remote I/O points will overload a ethernet network. If you have all managed switches that are properly configured using unicast connections, it would be highly unlikely you would saturate your network. However, when using unmanaged switches, especially if there is multicast multicast messages going on, you can easily start having networking issues. When you get more than just a few devices on a network, the types of switches and their setup starts playing a lot larger factor on network performance than just the raw number of devices on it.

 

[clegger]

This question is a lot more involved than if an X number drives, Y number of Controllers, and Z number of Remote I/O points will overload a ethernet network. If you have all managed switches that are properly configured using unicast connections, it would be highly unlikely you would saturate your network. However, when using unmanaged switches, especially if there is multicast multicast messages going on, you can easily start having networking issues. When you get more than just a few devices on a network, the types of switches and their setup starts playing a lot larger factor on network performance than just the raw number of devices on it.

I am very eager to learn more about all of this. Point me in a direction other than googling it to where I can learn more about everything you just said. Pretty please.

 

[James Mcquade]

clegger,

what are you calling a remote connection?
We have a star type plant / management fiber connection throughout the plant. if one line is cut, we have a backup. We also have a manufacturing network and a management network. Each is separate.

regards,
james

 

[clegger]

clegger,

what are you calling a remote connection?
We have a star type plant / management fiber connection throughout the plant. if one line is cut, we have a backup. We also have a manufacturing network and a management network. Each is separate.

regards,
james

Remote Connection as in just on my plant fiber connection that all of our office computers are connected to also. That way I can sit at my desk and go online with it "Remotely."

But engineering and I came up with just adding another ENET card in the bridge just for what I need. Engineering is okay with that. But would still like to look more into why the other ideas won't work.

 

[GTUnit]

This question is a lot more involved than if an X number drives, Y number of Controllers, and Z number of Remote I/O points will overload a ethernet network. If you have all managed switches that are properly configured using unicast connections, it would be highly unlikely you would saturate your network. However, when using unmanaged switches, especially if there is multicast multicast messages going on, you can easily start having networking issues. When you get more than just a few devices on a network, the types of switches and their setup starts playing a lot larger factor on network performance than just the raw number of devices on it.

Not really. If you have a couple of devices you can run them on a unmanaged, basic switch all day long.
You don't really need a managed switch unless you are doing some advanced routing or VLANS or something. Managed switches are not magic either and need "management". Last thing I want to try and configure are advanced switch settings.

IGMP snooping is the switch feature that is highly recommended and practically required for high device counts where multicast traffic is present.

 

[Toine]

We usually like to keep to unmanaged switches but have run into issues caused by one or two devices doing multicast or broadcast, bringing down part of a factory network. From that point on we have started using managed switches, but not for the advanced routing or VLAN stuff. We now use them for just a few simple reasons:

• multicast/broadcast storm protection
• traffic monitoring per port (where does all that traffic come from? how much traffic is coming from this device?)
• cable diagnostics per port (to quickly find where a cable defect is located)

The cost difference between an unmanaged and basic managed switch is negligible these days. For setup we have preset files that we can shoot into a new switch without further hassle. We keep records of IP addresses and label each managed switch with it's IP address.

 

[T Gibbs]

I use managed switches if I have Ethernet remote I/O because I don't want the I/O on the plant network. Configuration is very easy. I just set it up so the processor port sees every other port, but the network port only sees the processor and HMI ports.