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rut955 rut240 rut950 rutx11 rms vpn to openvpn wifi not sms trb140 firmware connection - ipsec on rutx12 rutx09 modbus
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RUT955 RS485 tty port issue.

0 votes
623 views 0 comments
by anonymous
Hi,

I have a RUT 955 and i would like to know which device in the /dev folder on openwrt os contains tty access to RS485... and which configure mode in the webui i need to set the RS485 interface to in order to be able to send characters to the tty and see any action on the RS485 port. Currently i have tried setting the RS485 to enable and Console mode or Only IP respectively but i get no response on the RS485 header pins with a fake termiation, that is 120Ohm resistor i 2Wire mode configuration. I have the outputs hooked-up to an oscilloscope and when running something like "echo "AAA" > /dev/ttyXX. I see nothing on the pins, even if i remove the artificial load still nothing on the pins.

Any input would be nice.

R.

3 Answers

+1 vote
by anonymous

I managed to get the rs485 work as a "raw" output TTY by putting the RS485 config to "Over IP" in the web interface after updating the RUT955 to the latest firmware ...07.12... I also noticed gliches on the RS485 bus with an oscilloscope this was due to the fact that.... Somebody have routed the damn transmit enabled pin to the data pin! What did Teltonika think here?!? This is NOT proper, i even opened the RUT955 open to confirm my suspicion and concluded that this was the case, result = usable but GLITCHY bus! If you run the RUT955 close to 115200 BAUD this will be particularly bad!

If one routes the TX pin to the TX_EN pin the transceiver will create a glitch every time an logical '1' is send to the pin activating the transmission circuitry, please fix this! the TX_EN pin should be activated separately as a function of available data in the shift register of the CPU so that TX_EN stays at a logical '1' for the whole duration of the bytes being shifted out from the buffers.

Teltonika you can do better, please revise this!

R.

Best answer
+1 vote
by anonymous
Hi,

I believe you're looking for /dev/rs485 and /dev/ttyUSB0, these both should work as controllers for RS485 connection.

EB.
0 votes
by anonymous
Can Teltonika confirm the problem with the RS485 Port ? Asking, because having problems with RS485-port on RUT955, too.