Ewon Cosy 131 accessing PLC

Hi, We have a Scada on a PC which fetches data from a PLC (S7-300) via TCP/IP connection, although this connection is no longer working. The IP family of the Scada is 192.168.0.1 while the Ewon and S7-300 are 10.101.31.230 and 10.101.31.231 respectively. The Scada PC, and S7-300 are both on the LAN side of the Ewon, while our site LAN is connected to the Ewon WAN.
Do I need to add some routeing of some sort to allow communication between the 2 different IP family? Remote Access/internet is not essential, I just need the connection for the Scada to work.
Would connecting the Scada PC into the WAN port of the Ewon and mapping the IP of the S7-300 to WAN IP via Nat1:1 allow communication?
Any help is much appreciated.

Hi,

NAT 1:1 would only help if the Scada was not connected to the Ewon LAN. The NAT would be able to give the PLC (S7-300) a Static IP on the same subnet it has set for the WAN connection and that IP will only work for devices that can reach the Ewon WAN (so your site’ LAN)

You did not mention what the site LAN is so I do not know if NAT 1:1 would help. If it is the same subnet as the Scada you will have to move the scada to connect on the WAN side of teh Cosy.

Otherwise you will have to change the IP address of teh Scada to be in the same subnet as the Cosy LAN and the PLC.

Hi Zach,
Thanks, I have quickly put together a basic topology of the network. So do you think it would work if I disconnect the ‘site lan’ cable (A) as internet/remote is not required for this network. And connect the cable B, to the WAN port of the Ewon? Then set a NAT1:1 route:
Device IP (LAN): 10.101.31.231
Mapped IP (WAN): 192.168.0.#.
Apologies I am still new to these things.
Thanks.EwonNetwork.pdf (18.3 KB)

With this Topogy it looks like the SCADA system will need it IP changed. Either it needs to be connected to your switch in LAN Site A and have its IP change to be in the 192.168.5.x range. If you do that you can use the NAT 1:1 feature on the Cosy to give the PLC a static IP in the LAN site network.

The other option is changing the IP to be in the 10.101.31.x subnet. the advantage of that is no setting on the Cosy would need to be changed and you would not need to move any cables. If they worry on that is not wanting users to be able to connect to the SCADA using the Talk2m service. You can specific specific IPs in the eCatcher software that can be accessed remotely and deny connections to other devices.

Hi Zach, thanks,
The scada side is more complex and has other devices/plcs so it would be desirable to change the ip of the HMI and S7-300 that is currently on the ewon network. Is there a way that this would work? Alternatively would an additional network card on the scada pc allow Wincc to add the S7-300 as a TCP/IP connection? The Scada only needs to reach the S7-300 in order to make a plot from sensor inputs connected to the S7-300.

If it is possible to change the IP of the HMI and S7-300 then yes those can be moved to be in the same network as the SCADA. If there is a programmer on site that can update the IP of those two devices that would be best. The Cosy would also need the LAN IP address updated.

As for the Scada. If it had a network card in the same IP range then it should be able to reach the PLC. In that setup the Cosy would just be acting as an unmanaged switch.