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I need to make a system with bidirectional communication between two RUT955 over TCP/IP. Both RUT955 receives data from its PLC via Modbus RS485 and sends data to a partner RUT955 which transfers data to its PLC over modbus RS485 (please see the attached file).

I tried doing all as mention in this example: "Bidirectional communication between two serial devices over TCP/IP" (https://wiki.teltonika-networks.com/view/Bidirectional_communication_between_two_serial_devices_over_TCP/IP). The idea in the example is the same as I need, only that I use rs485 instead of RS232. The only thing that i do different from the mentioned example is that I choose RS485 communication.

Also for the testing I configured both RUT955 in the local network, although later I will need to make a VPN tunnel between them.

Any suggestions on how to configurate the routers or where could be the problem?

I also can't find any diagnostics data on router to understand if it tries to send something or no. The only thing I tried is to connect a modbus testing device and according to it Master RUT955 sends data (only tx led is flashing) and client RUT955 does nothing (nor tx, nor rx led are flashing).

Will greatly appreciate all the help!

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Hello,

I suggest updating device's firmware to the latest version. The firmware file can be downloaded form here: https://wiki.teltonika-networks.com/wikibase/images/b/b1/RUT9_R_00.07.02_WEBUI.bin.

If the issue persists, could you provide a troubleshoot from both devices to review your configuration? To generate the troubleshoot file, access router's WebUI, go to System -> Administration > Troubleshoot section and download troubleshoot file from there.

Best regards,

Žygimantas

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Hello,

Sorry, for the long answer. I added a troubleshoot from both master and slave. I also got a sim cards with static IP, so I also tried configuration with them, but still nothing works. The troubleshoot files are made from the attemp with the sim cards.
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Hello,

I suggest trying to use ports shown at the example or at least higher than 1024. 

When in Over IP mode, the router is unaware about the protocol the data is transmitted in and simply acts as a transparent gateway between the nodes you want to connect. 

Other than that, your configuration seems correct, you have proper public IPs for both devices and based on the picture, your connector wiring is also correct.

For traffic monitoring, you can use either CLI tool TCPdump or Wireguard to see the traffic, which goes through your specified interfaces and ports. 

Best regards,

Žygimantas 

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Hello,

I tested a port number higher than 1024 and also as in example, but still nothing works. Is there any way to check in the router diagnostic if it receives something by rs485? I have a suggestion that Router does not understand that he receives something on RS485 port and as a result sends nothing to the slave.

It would be great if there were method how to check what happens in the Teltonika itself, cause at the moment it seems that RS485 just doesn't work or is disabled