RS2 Detects but Not Assign USB-to-UART via USB OTG

I’m trying to get NMEA data from RS2 firmware 28.4 to some radio with UART TTL interface. Because I don’t have RS232-EXT cable I use this cheaper alternative scheme(check the hyperlink):


The RS2 detects PL2303 USB-to-UART as:

Bus 002 Device 002: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port

But RS2 doesn’t assign PL2303 USB-to-UART to any /dev/tty*. I know this from the fact that the output command ls /dev/tty* doesn’t change whether the PL2303 USB-to-UART is installed or not. The output of dmesg | grep 2303 is also empty.

Beside when I use the browser interface to set the Position Output device to USB-OTG there is an error

Stream open error

The data LED indicator in PL2303 doesn’t blink at all, indicating there is no data from RS2.

I’m also sure this is not the hardware problem of PL2303 nor USB OTG since both working fine when I install it on my laptop that has USB-C port. Here some command output form my laptop:


Bus 001 Device 013: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port / Mobile Action MA-8910P

sudo dmesg | grep 2303

[ 6943.115706] usb 1-5: New USB device found, idVendor=067b, idProduct=2303, bcdDevice= 3.00
[ 6943.116750] pl2303 1-5:1.0: pl2303 converter detected
[ 6943.117299] usb 1-5: pl2303 converter now attached to ttyUSB0

Is there any USB-OTG device that actually works? Or I must resolve to user RS232-EXT cable?
system.log (7.8 KB)

Hi Achmad,

Did you check different baud rates? As you have UART radio on end, it may be non-standard.

Also, it’s worth checking if Reach RS2 outputs position in a more straightforward setup: from USB to PC.

I also saw your email. Please send the Full system report there. Just in case it won’t help, and we’ll need to go deeper.

The RADIO is irrelevant here as long as the RS2 data can’t get pass through the USB2UART. I’ve try all baud rate but it still doesn’t work. USB-PC mode is working because in this mode my PC acts as master and RS2 as salve. But I’m not interested in USB-PC mode.

I believe the core of the problem is RS2 Linux kernel doesn’t recognize PL2303 USB2UART as serial output in USB-OTG mode. In USB-OTG mode RS2 act as master and USB2UART as slave so in this mode RS2 will decide if an OTG is valid or not.

Hi Achmad,

It’s not a very common setup, so I don’t have a quick answer. Your assumption may be correct, but let me check the report you shared via email. Perhaps, it will give me more info. I’ll get back with the news soon.

Hi Achmad,

It took some time to check and test, but this adapter indeed isn’t supported in the Reach firmware. So, I’d go with RS232 cable. It should work for sure.

Is there any working case for USB-OTG position output? I mean the option is there, it should serve a purpose.

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Hi Achmad,

Yes, initially, it was designed for a USB radio.

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