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PLC is omitted and communication is lost.


PLC is omitted and communication is lost.

Hello community,
I am new here and would like to introduce myself first. My name is Steffen and I work as a project manager. I live in Germany in Baden Württemberg.

I have recently deployed a WinCC process control system in our production plant in Toronto/Canada to connect the production machines to the SAP MES system. In this case, the WinCC takes over the man in the middle function and reports the individual plant states and operating modes to the SAP world. Automatic product changes are also triggered from SAP and the machine then receives all production-relevant data from WinCC.

The network setup looks like this. There are 31 PLC stations of the type Omron CJ2M with the FINS Ethernet driver and 17 Omron NJ stations that are coupled to the Siemens WinCC OPC UA with the NJ Ethernet driver.
The individual PLC stations are collected using a Meraki switch and then connected directly to a redundant server system using two network cables.
So far so good.....The communication is established and the systems are running quite reliably. If a machine is now switched off by means of a main switch, the PLC is omitted and communication is stopped. Unfortunately, the communication then fails in the entire network.

And exactly here I need a little support from you.
Currently the configuration on the Kepserver is as follows. One CJ channel with all machines in one channel and all NJ machines also on one NJ channel.
I think to improve this I should create a channel for each machine and then create only one PLC in this channel. Can you confirm this or am I wrong here and my problem comes possibly from an incorrect setting within the two channels.
I would be very grateful for your help.







Greetings Steffen,

You can optimize the project if each machine has a different IP address to connect. 

For this, you may refer to the knowledge base article 


Mohit Rohilla



Thanks for reaching out in a private comment and letting us know that the previously provided steps didn't help much.

Could you please make sure Auto-Demotion is enabled for all devices in the single channel, or follow the steps below :

to separate devices on the Omron FINS Ethernet channel that they will need to multihome and then bind each new channel to one of the unique IP addresses created

Multihoming -
Some applications require users to associate a unique IP address with each channel. In these cases, the host computer must be multihomed; meaning, it must be configured to have more than one IP address. This may be accomplished by installing multiple Network Adapter Cards (NIC) in the computer or by assigning multiple IP addresses to a single NIC.

Adding IP Addresses to a Single NIC on Windows NT 
1. To start, click My Computer | Control Panel | Network. 
2. Click the Protocols tab and then select TCP/IP Protocol. 
3. Next, click Properties and then select the IP Address tab. 
4. Click Advanced | Add. 
5. Enter the additional IP address and subnet mask. 
6. Click OK.

Adding IP Addresses to a Single NIC on Windows 2000, XP, and 2003 (and newer)
1. To start, click My Computer | Control Panel | Network and Dial-Up Connections. 
2. Click Local Area Connection (or any other icon associated with the NIC of interest). 
3. Next, click Properties and then select Internet Protocol (TCP/IP). 
4. Click Properties | Advanced. 
5. Select the IP Settings tab and then click Add. 
6. Enter the additional IP address and subnet mask. 
7. Click OK.

Adding IP Addresses to a Single NIC on Windows Vista, 2008, and 7 
1. Click Start and then open Network Connections. 
2. Next, click Control Panel | Network and Internet. Then, select the connection that will be changed 
(such as the Local Area Connection). 
3. Click Properties, and then provide the administrator password or confirmation (if prompted). 
4. Select the Networking tab. Beneath This connection uses the following items, click Internet Protocol 
Version 4 (TCP/IPv4). 
5. Next, click Properties. Ensure that the connection is set to use an IP address by clicking Use the following 
IP address. 
6. Next, specify the IP address settings in the IP Address, Subnet Mask, and Default Gateway fields. 
7. To add a second IP address, click Advanced | IP Settings. Beneath the IP Address, click Add. Then, enter 
a new IP address and subnet mask.

Note 1: Windows NT can add up to five IP addresses for each NIC via the control panel. More IP addresses can be added to the registry manually as necessary. To browse, look under HEKY_LOCAL_MACHINE | SYSTEM | CurrentControlSet | Services. Then, select the service associated with the adapter card in question. Under the service, go to the Parameters | Tcpip subkey. Add the IP addresses to IPAddress and then edit SubnetMask and add an entry for each new IP address. Windows 2000 does not impose a limit on the number of IP addresses users add via the Control Panel, although the system may need to be rebooted before the new IPs can be used.

Note 2: There will be additional operating system overhead when running on a multihomed system. Unless users are using very fast devices, this overhead should not entirely cancel out the performance gain achieved from distributing the communications load over multiple channels.

for the NJ devices, those do not need to be multihomed, and can be separated each into its own channel just like other Ethernet based PLCs



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