Split ethernet networks

[marvis]

Hello everyone.

I have an PLC L35 (fmw 16) with address 192.168.1.1 and too many connected ethernet devices (3 hmi, a lot of ethernet port, asi slot, devicenet and 4 supervisors, etc..) and I need to create a different network for the supervisors, example 192.168. 2.xxx. so as not weigh down the network which starts to have communication problems and stop the line.

What solution can I adopt? Change plc? Which? Stratix?
Other solutions?

Thank you.

 

[OkiePC]

Never use the same IP address that every WalMart router comes with out of the box (192.168.1.1) for anything on a controls network. Always try to segregate HMI and PC Ethernet traffic from control related Ethernet traffic. If your CPU only has one Ethernet port, then everything that needs to connect to it must use that port, but if there is Ethernet/IP IO on that port, you'll want a managed switch to keep from peppering everything on that network with IO traffic.

I am not an expert in this area, and we probably need more details about all of your devices that need to connect with your PLC in order to give more specific advice.

 

[Mike__T]

What problems are you seeing that has lead to the conclusion that network communication problems are causing downtime?
What diagnostic tools have been used, and what were the results?
What are the network switch, or switches, makes and models used? Are they managed or unmanaged switches, or a mix of both?

The maximum number of nodes that can be connected on a single 192.168.1.xxx 255.255.255.0 network is 254 ( 256 - Network & Broadcast addresses)
However, I would not suggest anywhere near that number of nodes were put on a single network.
What is the node count of your network?

There could be a problem with the current network design that might be simple to resolve.

It is possible to segregate the existing network and create separate Automation and Supervisory networks.
It will require managed network hardware with Layer 3 Routing capability and VLANS.
Automation network devices on one VLAN, Supervisory network devices on another VLAN, and a Management VLAN.
Routing device configured with inter VLAN Routing to pass traffic between the two networks.
Switches configured with VLANs, and ports allocated to the VLANs for the devices.

No need to upgrade or replace the PLC.

I would recommend getting expertise with implementing Ethernet/IP segregated Automation networks to help with the design, network equipment selection, configuration and deployment if you decide to split the networks.
Yes, Allen Bradley Stratix range has suitable hardware. But, for managed networks, buying the correct network devices is only part of the solution.
The devices have to be correctly configured for the application before the network will perform as expected.

 

[TheWaterboy]

192.168.1.1 is about the worst possible address to use for anything but a gateway. Change that first and then provide more detail. Then change the entire network to get off that 192.168.0.0/24 or 192.168.1.0 /24 address range.

Based on the choices already made, you may be better off to hire some expertise to get this segmented the proper way.

 

[Aardwizz]

Do you really have more than 250 things that need to talk to the PLC?

Lot's of I/O, sure, and the HMI needs to read it too, and a few programmers.

But just because the HMI needs to read PLC tags on one network doesn't mean that it needs to serve up the graphics and data to its users ("Supervisors"?) on the same network. That would be the first thing to segregate: add a NIC to your HMI server so that PLC data is communicated on one network and all the graphics on another.

I don't believe that your CompactLogix doesn't allow more than the one native ethernet card, and it's a pretty old processor if you're running v.16. Upgrading to a L80 ControlLogix (which has a communication coprocessor built in to handle all the comms traffic while the main processor handles the logic) will improve your PLC performance greatly. You may not be experiencing "network" issues so much as the poor PLC having too much to do, and thus not being able to solve logic and command I/O in a timely manor.

With an upgraded processor, then you'll be able add ethernet modules to physically segregate your networks: one for I/O; one for HMI server data. Plus the third which doesn't touch the PLC, for the graphics. You can add more, if you want redundancy and the like, or to put ASI I/O on one network and Ethernet/IP I/O on another for troubleshooting purposes. But that's wish-list stuff.

You can play all sorts of games with your existing hardware with VLANs and subnet masks, but they won't make enough of a difference because you will still have all your eggs in the same basket. And baskets are awkward and eggs break.

This might not be cheap. But neither is downtime.

Good luck!

 

[marvis]

Good morning everyone and thanks so much for the replies that which were really helpful.
I'll try to explain the problem in detail.

I just recently joined this new company, which doesn't have other software engineers but they are electrical and mechanical in maintenance, so I have to try to get by on my own a little.

The problem I'm encountering is in particular on a stretch of line, sometimes I can see the plc under RSLinx but I can't connect to the software (it tells me that more users are already connected - but only I can connect) and it loses communication with the other production lines.
There are about 70 devices on the network (I mean the entire company network via arp -a scan from dos).
But as regards the "problematic" line section, it is made up of the L35 plc (fmw 16), 7 ethernet ports, 5 ASI slots, 3 IQ16A input cards, 1 OB16P/B output card, 1 devicenet card.
The CPU is only about 50% busy.

Thanks again.

 

[marvis]

I converted the plc sw with a new CPU, an L36erm; do you think it can solve the problem without intervening directly on the network?

Thank you

 

[JordanCClark]

Probably, although it's difficult to say without seeing the CPU load on the PLC.

The L35 supports 32 CIP and 32 TCP/IP connections. The L36ER supports 256 CIP connections and 120 TCP/IP connections.

 

[lfe]

If the only problem is random connection problems with the PLC, then perhaps there is a problem with the PLC's network wiring, for example, that it passes near power lines.

 

[L33er]

There is no such thing as L35.
There is L35E or L35CR which support 32 TCP/IP conn, Max CIP is 100.

What do you mean by 'I can't connect to the software'
but then ' but only I can connect')

 

[alan_505]

"What do you mean by 'I can't connect to the software'
but then ' but only I can connect')"

I think he means that he is the only one with the software onsite that is able to connect to the PLC.

 

[L33er]

This doc shows 32 CIP, 32 TCP/IP

https://literature.rockwellautomati...ure/documents/td/1769-td005_-en-p.pdf#page=43