USB baud rate using Teensy-based multiplexer

[Wayne Bennett]

I'm using a Teensy 3.2 to multiplex my NMEA data. The Teensy has 3 hardware UARTs as well as USB which I am using to send the mux'd data down to the Raspberry Pi 3 running OpenPlotter.

According to https://www.pjrc.com/teensy/td_serial.html the baud rate I set for the main USB Serial is ignored and communication is at full USB speed. I think this is causing kplex problems as although I can confirm data is being received at the ttyACM0 port by using Screen, I get no data and a timeout when using OpenPlotter's NMEA diagnostics tool.

I've tried: 

stty -F /dev/ttyACM0 38400 (my Teensy code sets Serial.begin(38400); for what it's worth)

I've checked that the udev rules file for the Teensy is in /etc/udev/rules.d/

[Keith Young]

I could be wrong (and anyone else please feel free to comment!) but I think if there's no UART to set (as there is with a serial-to-usb converter) as the teensy's documentation implies, baud doesn't matter.  What does the ttyACM0 section of your kplex.conf look like?  Try stopping kplex running as a daemon, then starting it manually form the command line, i.e.:

kplex -d3 file:

This should set up some basic debugging (-d3) and specify the command line as another interface ("file:") so you'll see anything coming into the multiplexer