M251 Multiple subnets and remote communication

[RaptorX303]

Hi,

I am hoping to acquire some help with control system network, specifically communicating with all my devices remotely. The devices I need to reach are on separate subnets, what I want is to be able to reach all of them from a single IP.

My setup is as follows:

-Schneider M251 PLC: This PLC has two Ethernet adapters and each has a unique IP address not on the same subnet.
Eth1- is the programming port, which also handles traffic between the HMI.
192.168.13.100
255.255.255.0
192.168.13.1

Eth2 - is the fieldbus port which handles Modbus TCP IO Scan to VFDs and other devices.
192.168.12.100
255.255.255.0
0.0.0.0

-I have a VFD connected to the Eth2 with an IP of 192.168.12.22
-My gateway device is an 3won VPN router with network settings as follows:
192.168.13.1
255.255.254.0

What I was hoping to achieve using a mask of 255.255.254.0 on the gateway device was to open up both the .12 and .13 networks to the 3won, so that when I VPN to it I can see both the PLC Programming port (192.168.13.100) and the VFD (192.168.12.22)

What is weird is that it kinda works. When I VPN to the 3won I am able to PING the PLC programming port (Eth1) (192.168.13.100) and I am able to PING the PLC Fieldbus port (Eth2) (192.168.12.100). But I cannot PING the VFD (192.168.12.22)

Any ideas why?

There is an article explaining how it can be done using an InHand gateway device instead of an 3won here: http://www.drivesandsystems.com/
(About halfway down the page)

But I was hoping to do it just by manipulating the network settings

 

[Operaghost]

My first thought is related to the mask. Based on what you included, I would have expected the drive to work, but not the eth2 adapter.

I would verify the subnet mask on all devices is 255.255.254.0 and that they are all pointing to 13.1 as their gateway.

OG

 

[AutomationCtrl]

RaptorX303

Unfortunately I do not have a resolution for you. However, I might be able to explain some of your observations. With a similar situation, I could not reach an elegant solution. The solution my customer and I came to with the 3won setup was to change the 3won LAN IP address to the required subnet as required- in your case. 12 or .13 depending on what we were doing. Also, since we didn't have a separate switch, we had to get someone onsite to move cables between ports- which is not practical in many cases.

For programming downloads, the 3won would have to be set to the .13 subnet but for device access ( VFD and eth2) the 3won had to be set to .12 ( adapting to your situation). However,when this happens, without an external switch, I'm unsure how eth1 will handle packets from the 3won intended for the .12 network- which I believe is why we had to physically move the 3won connection between those ports.

In your case, eth1 is responding as your 3won IP is on the same subnet. eth 2 is responding because there is a 'port' forwarding feature in eth1 's configuration in SoMachine ( though ping is ICMP based and not port specific- so maybe all messages are just forwarded along). You probably have it turned on already ( checkbox checked). I'm unsure why the VFD of the eth2 network isn't responding if eth1 is responding.

I have heard of a way to set the devices on eth2 up with some kind of gateway setting that would allow for it to respond to forwarded messages from eth1. However, eth2 gateway settings will not allow for a subnet other than .12. We couldnt get it to work with the time we had.
This is how I ended up with the multi-IP setting on the InHand device per the write up.

Maybe some of the more network savvy folks on here may be able to advise on covering these two subnets from the perpsective of the 3won and eth1 and eth2 settings.

_________________________________________
http://www.drivesandsystems.com

 

[RaptorX303]

Thanks for the responses guys I appreciate it

OG it looks like you were right, I changed the mask inside the drive to 255.255.254.0 and I was able to PING and connect with the SoMove software through the 3won

I ran a couple of variations, I put the gateway of the drive to 192.168.13.1 and also left it at 0.0.0.0. In both scenarios I was able to PING and connect through the 3won

So correct me if I'm wrong: since the drive had a different mask and was on a different subnet (.12) than the 3won (.13) the drive would not accept any incoming traffic from a different subnet. When I matched the masks the drive would now allow accept traffic from both the .13 and .12 networks.

To summarise my current settings

PLC - Eth1
192.168.13.100
255.255.255.0
192.168.13.1

PLC - Eth2
192.168.12.100
255.255.255.0
0.0.0.0

VFD
192.168.12.22
255.255.254.0
0.0.0.0

3won
192.168.13.1
255.255.254.0

 

[AGill]

For my own curiosity, is there is need for the gateway IP on Eth1? You don't seem to need it on the others.

 

[RaptorX303]

AGill,

"For my own curiosity, is there is need for the gateway IP on Eth1? You don't seem to need it on the others."

It looks as if it wouldn't be required, but when I removed the gateway address and connected to the PLC using SoMachine through the 3won it only stayed connected for about 30 seconds than disconnected itself. When I have the gateway address set to the IP of the 3won everything is ok.

Not sure if this is to do with networking or the SoMachine Gateway, because the Gateway is incredibly finicky especially in 4.1 SP2. Typically if I lose the ability to connect to a PLC either remotely or locally I have to do a full reboot of my PC.

 

[Zak Sawyer]

You can use an InHand IG601 or IR915 Router for the M251. It allows multiple gateways and subnets, and has been tested by many Modicon Engineers.

http://www.inhandnetworks.com/products/industrial-gateway.html