Hi all,

I have a raspberry-pi with an ethernet network interface (eth0) and a 4g modem interface (wwan0)

When I have an ethernet cable connected to eth0, I am able to connect to the codesys soft PLC running on the pi via the Codesys automation server.

But, when I disconnect the ethernet cable,CAS reports my Pi is no longer connected to the Automation server. (But the pi still has internet access via the wwan0 interface, i can ping external IP's and hit web pages from the terminal...)

I was wondering, is there a way to force the Linux Edge gateway running on the pi to use a specific network interface? (wwan0 in this case)

I should also mention that the IP address associated with wwan0 is a dynamic "10.116.xx.xx" address which is not publicly accessible/ routable through the internet.

Ideally I'd like to be able to install the device somewhere with just a 4G connection.
The device would maintain a connection with CAS, so I can remotely access the device to modify code/ troubleshoot using Codesys IDE.
Just wondering if anyone has implemented something similar? Or am I crazy and need to think of another way :)

Cheers,
Trent

Should work, does the Gateway stay green if you disconnect the ethernet cable in the CAS?

Thanks for your reply,

Yes the Gateway status icon always appears to stay green, regardless of whether the ethernet cable is connected or not, I guess that suggests the edge gateway on the Pi is using the wwan0 interface....

But, when I look in "list view", the status icon of the device changes to a red exclamation mark within a circle when i disconnect ethernet cable and I can no longer connect to the device via Codesys IDE.

This icon changes back to the debug icon when i reconnect the ethernet cable....

Is it possible I need to force the CodesysControl application to use the wwan0 port as well?

cheers,
Trent

Hi Trent,
this should work,

• Does a websocket connection work for you via the 4G modem?
  I have found the following project with which you can test it in the console: https://github.com/vi/websocat
  Alternatively, if you have RaspberryPI OS with graphilcal interface on the PI, you could with achromium/browser go to You Automation Server URL.
  If you see there the status of Edges + PLCs then also the Edge should be able to connect.

• If you uses the PI as edge gateway and PLC, will the 4G modem show both the edge gateway and the PLC as disconnected or only the PLC?

• If it was just the PLC, I would imagine that he might have a problem with the UDP broadcast.
• Then you could connect the PLC with the IP address, locally this should be possible even with "localhost".
  -> as an option Increase the log level of the Edge should also provide more information.

How to do this:
in /etc/Gateway.cfg

[CmpLog]
**CmpEdgeGateway.Filter=0xFFFFFFFF**
Logger.0.Name=/tmp/codesysedge.log
Logger.0.Filter=0x0000000F
Logger.0.Enable=1
Logger.0.MaxEntries=100000
Logger.0.MaxFileSize=5000000
Logger.0.MaxFiles=1
Logger.0.Backend.0.ClassId=0x00000104 ;writes logger messages in a file
Logger.0.Type=0x314 ;Set the timestamp to RTC

If you need more information - just use -> my question technical request/bugreport - we could investigate this on the system if needed.

a ok sorry did not see the answer bevor my post, if it stay green then the problem is:

"I would imagine that he might have a problem with the UDP broadcast"
Then you could connect the PLC with the IP address in the Edge Gateway here:
This should solve it!
picture follows

Hi @eschwellinger

Thanks very much for your responses - I ended up changing the IP address to localhost and that has fixed the issue for me :)

regards,
Trent