Network IP routing, device on different IP range

Hi

How can I setup a connection with different IP`s on the controller and the device?

So routing the subnet IP. The controller being 10.98.53.50 and the device need to be on 10.98.50.150.

HW does not allow to have different IP ranges in same subnet.

This is a existing MES network that communicates over the factory with machinelevel PLC. I want to utillize the same network and controller to collect signals from a device, (in this case EH Promag flowmeter). The existing controller is made with V5.5.

Existing network is made with Cisco equipment. IP is splitted with different IP ranges in the different areas of the factory. Existing controller is communicating with 60 other PLC`s. But communicating with a device is something else, then we somehow need the "GSD" in the HW.

Help would be highly appreciated.

BR Stefan

[Update: fixed typos]


Are you saying that on the MES network

• all nodes (IP Addresses) are either 10.98.50.0/255.255.255.0 (a.k.a. 10.98.50.0/24) or 10.98.53.0/255.255.255.0 (10.98.53.0/24)?
• there are only switches connecting all nodes, and no routers or gateways?

So the two nodes you want to communicate (existing controller and new(?) device) are on the same physical* network, but a different logical network.


* sometimes called "broadcast domain"


If yes, then one solution might be a non-NAT router or gateway with two Ethernet ports, both ports connected to the same MES network, one port configured as an IP address on 10.98.50.0/24, and one on 10.98.53.0/24. But then every .50.0/24 node would be able to communicate with every .53.0/24 node, unless the router/gateway could be configured to filter packets based on IP address.



An alternative might be to change the netmasks on those devices to 255.255.0.0, but that might have unintended consequences.

Thanks for quick answer.
I see I am a bit unclear...

The existing network has a main controller (S7 412 2-PN). With IP 10.98.53.50 Mask 255.255.255.0 GW: 10.98.53.1
This PLC is communicating with 60 other PLC split into areas with smart switches, also routing the IP. Example 1 of the 60 communication partners has IP 10.98.55.50 Mask 255.255.255.0 GW 10.98.55.1
This is still functioning perfectly after 10 years. But this is setup in Netpro with connections and gateways.

Now my question is how to communicated over this network with an device, the device I want to be on a IP range of 10.98.50.xx.
As I see it the device has to be setup in the hardware with the GSD file. But how to do that when HW only allows 1 subnet to be setup?
And how to link these to subnets together?

All network infrastructure should be in place. But somehow the configuration needs to know how the network is routed.

I have seen a PLC dedicated to collecting information just for MES, where the PLC can be configured to message a variety of networks if the syntax is correct.

The controller (10.98.53.50) only needs to know, and already does know, that is has to use default gateway 10.98.53.1 to get to any IP address not on 10.98.53.0/255.255.255.0, which includes the new device at 10.98.50.150.



So the "router/gateway" that accepts traffic sent to 10.98.53.1, and is the default gateway for 10.98.53.0/255.255.255.0, needs to be configured to know how to route packets to 10.98.50.0/255.255.255.0.


And the "router/gateway" that accepts traffic sent to 10.98.50.x (.x = .1, presumably). and is the default gateway for 10.98.50.0/255.255.255.0, needs to be configured to know how to get to 10.98.53.0/255.255.255.0.



TL;DR



Default gateway means the gateway to use for any IP address that is not either

• To a local address i.e. same a.b.c.d/m.m.m.m
• To a specific address configured using a non-default gateway (unlikely here, but possible)

So the original two networks (subnets) i.e. network-address/netmask/default gateway):

• 10.98.55.0/255.255.255.0/10.98.55.1
• 10.98.53.0/255.255.255.0/10.98.53.1

And the device is on a new third network,

• 10.98.50.0/255.255.255.0/10.98.50.x (.x is probably .1)?

Is there only one router between the original two networks? how many ports does that router have? Or is all the routing configured in the smart switches?



How is the new third network connected to the original two?

The network is setup with the "toplayer" being the MES PLC. At IP 10.98.53.50
Thru fiberoptics to the different factory areas, local patching cabinet where we have a smart switches.
I can ping the "device" thru the network. But how to set it up in the Siemens HW? preferable if it can be done in Simatic V5.5 (But if needed we could upgrade, if newer versions provide this function).
The device (Endress Hausser Promag flowmeter) comes with a GSD file. Witch is needed for the communication, how can I put that in the Simatic setup?

Here's a thought? Does the PLC have a spare ethernet port that you could assign an address to on the other network?

Another alternative might be to change the subnet mask from class "C" to Class "B". With any subnet mask, a bit set to 1 indicates that the corresponding bit in the IP address is part of the network number so with address 10.98.53.50 and mask 255.255.255.0 then 10.98.53.xxx is the network number and x.x.x.50 is the computer number within that network. Changing the subnet mask to 255.255.0.0 would indicate that both devices are in the same network. This may have other consequences for routing and traffic locally so best to check with IT if it part of an MES system.

Nick

it sounds like the network is working and OP can ping through to the other subnet.

What the OP is really asking is how to config the software to connect and I can't really help with that as I'm unfamiliar with Siemens.

the one confusing part is this

"HW does not allow to have different IP ranges in same subnet."

Do you mean it won't allow you to enter IP of the OTHER device in another subnet? I have never seen anything like that. so if that's the case it would be helpful to give us a screen shot.

Stefan, when you say communicate to a device, you mean via Profinet, correct, not an S7 or TCP connection?


Profinet does not support routed IO data, because the IP address doesn't actually appear in the ethernet packet. You would need some kind of PN aware gateway to perform the translation.

Yes, it is profinet.
I also tried to open the mask to be able to config different IP`s. So then Simatic did allow to have different IP in same subnet but still no connection.
The device has a option for diagnostics, verification and setup. Over web browser. (That is why the profinet device has IP setup). Over the web browser I can reach the device from PLC side. But the PLC cannot reach it.
Now I am aware of that the realtime profinet does not support routing. But for "non-time-critcal" tasks profinet uses TCP/IP. Is it possible to specify it to be "non-time-critical"?
How do the profinet know that it is being routed?
The network has smart switches that also does the routing. Would my setup work with profinet if I avoid routing? (only switching).

My alternative (which I am trying to avoid) is to install local PLC`s. That will communicate with the device, and then the main PLC will collect the data from there.

Stefan Ihlen said:

Yes, it is profinet.
I also tried to open the mask to be able to config different IP`s. So then Simatic did allow to have different IP in same subnet but still no connection.
The device has a option for diagnostics, verification and setup. Over web browser. (That is why the profinet device has IP setup). Over the web browser I can reach the device from PLC side. But the PLC cannot reach it.
Now I am aware of that the realtime profinet does not support routing. But for "non-time-critcal" tasks profinet uses TCP/IP. Is it possible to specify it to be "non-time-critical"?
How do the profinet know that it is being routed?
The network has smart switches that also does the routing. Would my setup work with profinet if I avoid routing? (only switching).

My alternative (which I am trying to avoid) is to install local PLC`s. That will communicate with the device, and then the main PLC will collect the data from there.

Click to expand...

"Non-time-critical" in the context of Profinet means things like paramaterization of the IO, and maybe diagnostics. It isn't a selectable option. There is technically a "PN over TCP" in the PN spec, but my understanding is that it is considered legacy and I've never heard of it being implemented.


The Profinet doesn't "know" it is being routed. It is simply not possible, because there is no IP header in the PNIO data traffic. PN data is designed to stay within one local network, and IP is a standard created to allow communication between networks. Routing can add significant latency and jitter that would be unacceptable in most IO networks.



Opening the subnet mask will allow the messages to be sent, but the network must still be configured correctly. The PN controller and PN device must be on the same Layer 2 network. In theory, if you are only doing switching and not routing, that should work. If there is an IT team involved, you may need to consult with them, to ensure that this change doesn't have other impacts.


Adding a remote PLC as a data collector/forwarder would be another potential solution, as you said. Something like an S7-1200 would be relatively inexpensive, although you'd need TIA Portal for it.

Thanks for all support.

I done testing on different solutions but with this actual setup I have not succeeded.

The solution will be to have a local PLC with Profinet to the device. And then collect the data from this local PLC. Anyway I am happy with this solution because the network structure will be kept and compliant to IP ranges.

But interesting to check this out and get some learnings out of it. So findings was that even tough IP was only switched over the network I could not get the communication up. Pinging the IP worked. (IP used for web option/diagnostics). Probably the profinet is not compatible with the equipment on the network. The network consist of several "smart" switches and fiberconverters.

BR

Stefan