Serial to IP not (fully) working for rs232

Hello,

Summary
The Serial to IP with the rs232 is only partially working. Serial to IP is working, but IP to serial is not, and make the service stalled.

Configuration

In this pictures, we can see that RX data is incrementing (correctly) and that TX data is only incrementing partially.

rs232 → IP (3x): OK
IP → rs232 (2x): not received
rs232 → IP (3x): OK
IP → rs232 (3x): not received, and Serial to IP service is stalled!

After switching OFF the service with the web interface, the COM did received part of the data only!?

rs232 test in CLI

“Printing” out the data received from the rs232 on the console works fine.

Sending data to the rs232 only worked when sending small amount of data. It blocked after 64 bytes while sending bigger chunk. Also, the echo doesn’t work if cat < /dev/rs232 is running in another console.

rs485
I did test the rs422 (rs485 full duplex), and it works just fine. Send, receive, small and big chunks, using the CLI with both cat and echo at the same time.

I haven’t spot anything strange here either…

root@RUT956:~# stty -F /dev/rs232
speed 9600 baud; line = 0;
intr = ^C; quit = ^; erase = ^?; kill = ^U; eof = ^D; eol = ; eol2 = ; swtch = ; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost -onlcr
-isig -icanon -iexten -echo -echoe -echok -echoctl -echoke
root@RUT956:~# stty -F /dev/rs485
speed 9600 baud; line = 0;
intr = ^C; quit = ^; erase = ^?; kill = ^U; eof = ^D; eol = ; eol2 = ; swtch = ; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost -onlcr
-isig -icanon -iexten -echo -echoe -echok -echoctl -echoke

Thank you for your suggestions.

Sincerely,
Jerome

Hello,

I am going to test this and will come back to you with more information.

Regards,
M.

Hello,

I was not able to reproduce the issue, or at least did not see any data being lost:

What firmware are you using? Do you have a different RS232 cable you could try and test?

Regards,
M.

Hello @Matas,

  • It’s running the latest firmware: RUT9M_R_00.07.15.2
  • I looped back the cable I use (+NULL modem) on another different COM port on my machine, and it works well.

Sincerely,
Jerome

So the issue, I suppose, is then related to the cable/ports, then?

Regards,
M.

No, sorry for the misunderstanding.
I looped the COM port that was connected to the RUT956 to another COM port on my machine, so both COM port on my machine and the cable are working.

Since I’m unable to reproduce this issue, I’ll need to collect a troubleshooting file from your device. Since it contains sensitive information, we’ll have to do this in private. I’ve sent you a form to fill out, in the ticket ID field simply fill in “14554” and I’ll reach out to you via email.

Regards,
M.

Release RUT9M_R_00.07.16.1 from 2025-07-17 seems to have fix it.

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