Question

This is an issue related to this question that has not yet been resolved.

An RS422 device transmitting data is connected to the RUT955 RS485 port. Proper connection and transmission have been verified. In Console mode, the CLI command cat /dev/rs485 shows the incoming data from the RS422 device.

Switching to Over IP mode and with the same serial port configuration, no data appear in the terminal.

Firmware version is the latest RUT9_R_00.07.03.2

Answer 1

Hello,

I think I have have replicated your scenario. I'd like you to confirm it, before taking it to the developers. Below is a screenshot with a serial terminal acting as a serial device on the left and the end host listening on port set in over IP configuration on the right. The end host does receive data, but there is no trace of it in the terminal.

Is the issue that the terminal is not displaying input data?

Does the receiving end get the data?

Best regards,

Comments

I confirmed the issue in the following way.

I connect the transmitting device to the RUT955 RS485 port. The device continuously transmits data.

Configuring the RUT955 serial service to enable RS485 in console mode, from the cli using the command cat /dev/rs485 I can see the incoming data.

Without any other change,  I configure RUT955 to enable Over IP mode using the RS485 port. From the cli I cannot see any data. Of course, nothing seems to go to the UDP server I have defined.

Switching back to Console mode the cli command shows incoming data again.

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Hello,

Are you able to ping the 

I have done some testing, but did not encounter the issue. Device does send data even in Over IP, when UDP is used as transport protocol.

Instead of using cat /dev/rs485, I'd like you to try the following:

Login to the router via SSH, make sure you have internet connection, as I'd like you to download additional package using these commands:

• opkg update
• opkg install tcpdump

Then enable packet capture by modifying the below command according to your settings:

• tcpdump -i <interface> dst <destination_IP> and dst port <destination_port>

In my local setup, I had a UDP socket at 192.168.2.113 address listening on port 5555, thus my command looked the following:

• tcpdump -i br-lan dst 192.168.2.113 and dst port 5555

Similar output should be received, when data is sent:

Lastly, I would like you to attach a troubleshoot file to your question. Please, replicate your configuration, then access router's WebUI, go to System -> Administration -> Troubleshoot section and download troubleshoot file from there. The logs in the file might provide more insight into the issue.

Best regards,

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Thanks for you reply.

Before going on please clarify. Should I see incoming data from the RS485 port in Over IP mode as I do in Console mode or not? For that part, see my screen recording on Youtube.

Although I do not understand the usefulness of using tcpdump in my case (where first of all no data appear in the RS485 port). Howwever,  I executed the steps you suggested. I performed two scenarios, first configuring a local network recipient at 192.168.1.13 and second an Internet recipient (that is my real need) at 178.xxx.xxx.143, port 6699 in both cases.

https://community.teltonika-networks.com/?qa=blob&qa_blobid=16404782192333841295

https://community.teltonika-networks.com/?qa=blob&qa_blobid=7826161310375098765

As expected no data traffic appears. I would suggest watching carefully the screen recording to see how in Console mode data appear from the rs485 port but not in Over IP mode.

Troubleshoot file was also uploaded (but deleted afterwards since it appears in public)

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Please send the troubleshoot file in a private message here. A description of a connected device might be helpful too. I will consult RnD. Hopefully they will provide more insight.

The way I found it to work is that in Over IP mode, data is not transmitted to the remote host if cat /dev/rs485 is being executed, but the command displays input data. If cat /dev/rs485 is not being executed, data is successfully transferred to remote host. In either case, input data was still visible.

Best regards,  

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Troubleshoot file sent by PM. 

Do you use firmware RUT9_R_00.07.03.2?

The device connected to the RS485 is an AIS receiver equipped also with a GPS receiver. The GPS receiver is set to continuously transmit NMEA sentences for test purposes. It has an RS422 output set to 38400, N,8,1 and is connected to the RS485 port, D+ to pins 5 & 4 and D- to pins 1&2. As mentioned, in Console mode the command cat /dev/rs485 show the incoming data (also shown in the screen recording). Switching directly to Over IP mode, data are not sent to the destination IP:port using UDP nor shown in the terminal using cat /dev/rs485