Ethernet/IP Performace Tips

Does anyone have any experience with the ab stratix 8000 managed switches?

I am looking at them for an application that currently has about 20 power flex drives and 14 blocks of point I/O as well as 3 compactlogix processors and two versa view panel pc’s of which one is an rsview server and the other is it’s client.

The comms on this system absolutely crawl. Currently it is using hirschmann spider non managed switches.

I have already checked all connections. The system has run this way from day one but over time a couple drives have been added and it made it much worse.

Turning a valve on/off for example from the rs view application takes 10-15 seconds for the button/display to update and the same for vales to change after they are entered. I have been doing some reading on switches and I am almost sure that this will be a vast improvement. Does anyone have any other tips or suggestions to improve the speed and performance of an Ethernet/ip network?

You probably need a switch that has IGMP snooping. This feature will help control multicast traffic, which will help smooth out network traffic. If you talk to Rockwell they will always tell you to put a managed switch with IGMP snooping.

The managed switch can be used to limit the multicast traffic from the I/O to just the ports that need it. The unmanaged switch already does this for unicast traffic like the client to the server. If this will increase your performance or not depends on your design.

I'll assume that your processors are on the same network to talk to the HMI. Each processor probably has it's own I/O blocks. The improvement will come from blocking the "foreign" I/O blocks from each processor. If this is a significant protion of the traffic, you may see an improvement.

Map out your comms. Analyse the network and find out where the limits are. Ideally, the I/O for each processor would be on a separate network, but you can achieve similar performance with a managed switch unless you exceed the backplane bandwidth of the switch.

There a 3 processors all on the same network talking to the hmi and drives as far as i/o each processor has its chasis based i/o ,local i/o ,it is compact logix so chasis based i/o is not the correct term but you get the idea.

The point i/o and everything else is all on the same network.

Are you saying that i would get better performance if i put the point i/o and drives with their respective processor and on a seperate network and have 3 seperat networks talking to the hmi? there are some comms form plc to plc that happen without the hmi so how should that be handled? Messages?

Sorry for writing a book but i am learning ethernet as i go and as it breaks.

HMIs can be bandwidth hogs. Make sure the HMI is only asking for the data it needs and at a rate not faster than what people can read the data.

If you are using the EthernetIP I/O you can slow down the packet interval. I think default is 10 ms. This is often much faster than what is needed.

I think you have two good options. The IGMP switch or getting two additional Ethernet cards. It has been done before. I have seen systems with 4 Ethernet cards in them. If this is for your plant then eventually you will want to learn about the IGMP snooping. If you are an integrator and time is money then getting the extra Ethernet cards may be a better way to go.

The Ethernet cards should route the messages between them automatically. You just need to set up the IP Address and mask correctly. The Ethernet cards will pass packets that have destinations on their bus and block the others. I haven't figured out what this does to the Rockwell back plane. It would seem to me it could get awfully busy if there is much traffic between the buses.

These systems should have been built with managed switches in the first place. Whenever I see Spider switches, I just know that an OEM has taken advantage of a customer who thought all he had to do was specify "Hirschmann" and he would get a managed switch.

The Stratix 8000 are very high performance, and would do a fine job of restricting the I/O packet traffic to the ports that need it, so it doesn't blind the HMI system.

If this system needs high availability or security, then the premium for the Stratix 8000 switches is worth it. They can provide statistics and status information directly to the CompactLogix controller program, and have plenty of horsepower. IT guys like them too because they use the familiar Cisco IOS operating system.

Some other options include the smaller Stratix 6000 switch, or the Hirschmann RS20 or the N-Tron 508TX-A. Don't buy those cheap Aaxeon switches, unless you want to replace them too.

What you're looking for, as others have mentioned, is IGMP Snooping and Querying. Most managed switches have those functions.

Use a web browser to figure out how many packets/second are running on each CompactLogix, and how many Connections are in use. That might be useful information to figure out how to decrease the load on the Ethernet ports of the CompactLogix.

Peter

What would be the slowet update time i would want to set typically. i know you said that 10ms was default how high shoul i normally set this. The primary info the hmi is getting is temps and drive speeds/regen amounts so it does not have to be fast.

It is slow as a snail now and it is workable so it can only get better from here.

The Plc Kid said:

Peter
What would be the slowet update time i would want to set typically.

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That is application dependent.

i know you said that 10ms was default how high shoul i normally set this.

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I would try 50ms. If that doesn't work you have a serious problem. If 50ms is fast enough you might leave it there. If not then try reducing the RPI by 10ms at a shot. Note, not all devices need to be adjusted to the same RPI. You can try slowing some slow input modules down to 100ms if it will not affect performance.

HMIs don't need to update any faster than 200ms-250ms. You can't read the changing numbers if you update faster.