3 Replies Latest reply on Jul 10, 2015 9:19 PM by John_Quin

    Multiple USB Serial from OTG and Hub, possible?


      Hi All

      I am having some difficulty with getting two USB serial ports running off a OTG cable and hub.


      OS is UBILINUX on an edison minibreakout board


      I have had a few false starts with fake prolific chipsets and low quality hubs but I now have something that boots (every second time *sigh*) and shows both a /dev/ttyUSB0 and a /dev/ttyUSB1. So one is a prolific driver and the other a FTDI. I had to add the FTDI driver myself but running on its own it works reliably.


      lsusb -t shows two devices off the same hub as expected.


      So the issue I have is the FTDI device falls over when I start reading from the prolific one. I've tested power brown out and supplied independent power so that is not the issue.

      The two devices are running different bauds but really they should be fully independent from a software/OS perspective.


      Any ideas?

        • 1. Re: Multiple USB Serial from OTG and Hub, possible?



          After doing some reading on what might be the possible cause of your issue I found that several users who have had issues with the OTG pot is related to the ID of the grounding pin. There is a full discussion on this here Re: connecting directly to the OTG port . If this is not the solution then I’d suggest you to check the output of lsusb and dmesg to see if you get a clue on what might be going on.


          Also, you can post your question in the emutex website EmutexLabs since they are the ones who support the ubilinux image and might provide a more accurate response.



          • 2. Re: Multiple USB Serial from OTG and Hub, possible?

            OK so I managed to use minicom to eliminate the OS and drivers as being the issue.

            It looks like one of the applications I am using to read the serial ports is doing something bad.

            • 3. Re: Multiple USB Serial from OTG and Hub, possible?

              Great so I finally got the program working (Still some stuff to do to get it work automatically from cold boot )


              The application was logging PV solar enegy generation and uploading it to pvoutput.org as well as energy consumption

              The hardware is an Aurora PV inverter with RS485 to USB converter (FTDI) and Current Cost ENViR logger. (uses prolific)

              The applications were Auroramon 1.07 and pvoutput intergration service


              It looks like pvoutput has an auto detect feature that cycles through the serial ports and even when you manually specify the port it interferes with others

              I solved the issue by creating another user and letting pvoutput work in that one where it didn't have permission to screw things up.


              Anyhow most others doing this kind of thing are using Raspberry PI, so edison is now an alternative