Question

The router worked well as a  RS232 serial device server for many month, but now the service stopped working. RS232 is disappeared from webgui and via ssh I figured out that /dev/rs232 is missing.

Following the not working router:

root@PLS-MBA-PARKHAUS:~# ls -la /dev/

drwxr-xr-x    5 root     root          1160 Jul 30  2022 .
drwxr-xr-x    1 root     root             0 Jan  1  1970 ..

...

lrwxrwxrwx    1 root     root            12 Jul 30  2022 rs485 -> /dev/ttyATH1

lrwxrwxrwx    1 root     root             8 Jan  1  1970 shm -> /tmp/shm

crw-rw-rw-    1 root     root        5,   0 Jan  1  1970 tty

crw-rw----    1 root     dialout   252,   1 Jan  1  1970 ttyATH1

crw-rw----    1 root     dialout     4,  64 Jan  1  1970 ttyS0

crw-rw----    1 root     dialout   188,   0 Mar  2 10:25 ttyUSB0

crw-rw----    1 root     dialout   188,   1 Jul 30  2022 ttyUSB1

crw-rw----    1 root     dialout   188,   2 Mar  2 10:25 ttyUSB2

crw-rw----    1 root     dialout   188,   3 Jul 30  2022 ttyUSB3

crw-rw-rw-    1 root     root        1,   9 Jan  1  1970 urandom

crw-------    1 root     root       10, 130 Jan  1  1970 watchdog

crw-rw-rw-    1 root     root        1,   5 Jan  1  1970 zero

Following a comparisson with a working router, same configuration:

root@PLS-MBA-TIEFGARAGE:~# ls -la /dev/
drwxr-xr-x    5 root     root          1220 Jul 10  2022 .
drwxr-xr-x    1 root     root             0 Jan  1  1970 ..
...
lrwxrwxrwx    1 root     root            12 Jul 10  2022 rs232 -> /dev/ttyUSB0
lrwxrwxrwx    1 root     root            12 Jul 10  2022 rs485 -> /dev/ttyATH1
lrwxrwxrwx    1 root     root             8 Jan  1  1970 shm -> /tmp/shm
crw-rw-rw-    1 root     root        5,   0 Jan  1  1970 tty
crw-rw----    1 root     dialout   252,   1 Jan  1  1970 ttyATH1
crw-rw----    1 root     dialout     4,  64 Jan  1  1970 ttyS0
crw-rw----    1 root     dialout   188,   0 Mar  2 09:55 ttyUSB0
crw-rw----    1 root     dialout   188,   1 Jul 10  2022 ttyUSB1
crw-rw----    1 root     dialout   188,   2 Jul 10  2022 ttyUSB2
crw-rw----    1 root     dialout   188,   3 Mar  2 09:55 ttyUSB3
crw-rw----    1 root     dialout   188,   4 Jul 10  2022 ttyUSB4
crw-rw-rw-    1 root     root        1,   9 Jan  1  1970 urandom
crw-------    1 root     root       10, 130 Jan  1  1970 watchdog
crw-rw-rw-    1 root     root        1,   5 Jan  1  1970 zero
root@PLS-MBA-TIEFGARAGE:~# ps | grep sodog
 1491 root       984 S    /usr/sbin/sodog -p /dev/rs232 -b 8 -s 9600 -a none -t 1 -m server -D 0 -c 300 -i 0.0.0.0 -g 17184 -R -L 32 -w 0
13649 root      1592 S    grep sodog

Uses Firmware RUT9_R_00.07.02.7

Is this a harware problem or an software issue?

Answer 1

Hello,

It is most likely a hardware issue.

As a suggestion, you could try performing device recovery by flashing firmware via bootloader menu. For instructions, refer here.

If that does not help, contact your reseller and return the device for a replacement or warranty repair. 

Based on your serial number, it should still have a valid warranty.

Best regards,

Answer 2

I changed the defective router yesterday and the system works fine.

Now I'm checking the defective router and it seems that there happened a miracle of self healing because after a day without power the RS232 interface is reappeared and the serial device server works.

Any idea for that phenomenon and how to avoid this in future?

Comments

Have you noticed the circumstances, when RS232 service stopped working? Maybe you have experienced some power failure, or some momentary voltage surge?

Have you performed a firmware update?

It is not usual for the RS232 device to disappear, thus difficult to estimate what caused it, and if it is possible to prevent it from happening.

Considering that the RS232 is completely absent from the troubleshoot file details, it seems like faulty hardware.

Best regards,