On Wed, 7 Oct 2020 11:43:50 +1300, Wolf via lazarus <lazarus@lists.lazarus-ide.org> wrote:
>By submitting your question to DuckDuckGo, I found >https://stackoverflow.com/questions/2530096/how-to-find-all-serial-devices-ttys-ttyusb-on-linux-without-opening-them > >To quote: > >|To see which tty's are currently in use, you can simply look into the >file /proc/tty/drivers: and get a rather short list of devices. |Does it help? OK, I have read through your link and also tested a lot on an RPi4 and a standard i386 Ubuntu server. The suggested file is no help since it contains a lot of irrelevent stuff. This is what I have found that is closest to what I need: Ubuntu 18 server, where I have one USB serial adapter installed: --------------------------------------------------------------- $ ls -l /dev/tty* | grep 'dialout' crw-rw---- 1 root dialout 4, 64 Sep 26 23:45 /dev/ttyS0 crw-rw---- 1 root dialout 4, 65 Sep 26 23:45 /dev/ttyS1 crw-rw---- 1 root dialout 4, 74 Sep 26 23:45 /dev/ttyS10 crw-rw---- 1 root dialout 4, 75 Sep 26 23:45 /dev/ttyS11 crw-rw---- 1 root dialout 4, 76 Sep 26 23:45 /dev/ttyS12 crw-rw---- 1 root dialout 4, 77 Sep 26 23:45 /dev/ttyS13 crw-rw---- 1 root dialout 4, 78 Sep 26 23:45 /dev/ttyS14 crw-rw---- 1 root dialout 4, 79 Sep 26 23:45 /dev/ttyS15 crw-rw---- 1 root dialout 4, 80 Sep 26 23:45 /dev/ttyS16 crw-rw---- 1 root dialout 4, 81 Sep 26 23:45 /dev/ttyS17 crw-rw---- 1 root dialout 4, 82 Sep 26 23:45 /dev/ttyS18 crw-rw---- 1 root dialout 4, 83 Sep 26 23:45 /dev/ttyS19 crw-rw---- 1 root dialout 4, 66 Sep 26 23:45 /dev/ttyS2 crw-rw---- 1 root dialout 4, 84 Sep 26 23:45 /dev/ttyS20 crw-rw---- 1 root dialout 4, 85 Sep 26 23:45 /dev/ttyS21 crw-rw---- 1 root dialout 4, 86 Sep 26 23:45 /dev/ttyS22 crw-rw---- 1 root dialout 4, 87 Sep 26 23:45 /dev/ttyS23 crw-rw---- 1 root dialout 4, 88 Sep 26 23:45 /dev/ttyS24 crw-rw---- 1 root dialout 4, 89 Sep 26 23:45 /dev/ttyS25 crw-rw---- 1 root dialout 4, 90 Sep 26 23:45 /dev/ttyS26 crw-rw---- 1 root dialout 4, 91 Sep 26 23:45 /dev/ttyS27 crw-rw---- 1 root dialout 4, 92 Sep 26 23:45 /dev/ttyS28 crw-rw---- 1 root dialout 4, 93 Sep 26 23:45 /dev/ttyS29 crw-rw---- 1 root dialout 4, 67 Sep 26 23:45 /dev/ttyS3 crw-rw---- 1 root dialout 4, 94 Sep 26 23:45 /dev/ttyS30 crw-rw---- 1 root dialout 4, 95 Sep 26 23:45 /dev/ttyS31 crw-rw---- 1 root dialout 4, 68 Sep 26 23:45 /dev/ttyS4 crw-rw---- 1 root dialout 4, 69 Sep 26 23:45 /dev/ttyS5 crw-rw---- 1 root dialout 4, 70 Sep 26 23:45 /dev/ttyS6 crw-rw---- 1 root dialout 4, 71 Sep 26 23:45 /dev/ttyS7 crw-rw---- 1 root dialout 4, 72 Sep 26 23:45 /dev/ttyS8 crw-rw---- 1 root dialout 4, 73 Sep 26 23:45 /dev/ttyS9 crw-rw---- 1 root dialout 188, 0 Oct 7 09:34 /dev/ttyUSB0 RPi4, where I have 2 USB connected serial devices: -------------------------------------------------- $ ls -l /dev/tty* | grep 'dialout' crw-rw---- 1 root dialout 204, 64 Sep 23 17:57 /dev/ttyAMA0 crw-rw---- 1 root dialout 188, 0 Oct 6 12:33 /dev/ttyUSB0 crw-rw---- 1 root dialout 188, 1 Oct 6 15:08 /dev/ttyUSB1 Obviously the Ubuntu situation is a non-starter since it lists way too many ports than can possibly be accessible. In fact on that computer ONLY the USB adapter is possible to use, I don't know where the others might be... But the RPi4 result is more promising since it lists the 3 ports I know are there and none else. But concerning the USB connections there is a different problem too, the port name depends on in which order the adapter is plugged into the USB socket, the first plugged adapåter gets ttyUSB0 and the next ttyUSB1 etc..... So if you want to select the correct port wired to a specific device you are in a random situation. I have had to set up the RPi system such that it creates a symlink to the plugged in usb-serial adapter based on the ID of the USB socket it is connected to. This is done by editing the file: /etc/udev/rules.d/99-usb-serial.rules By entering rules for the USB sockets as follows I have locked down the tty name for each socket such that it will be a constant. SUBSYSTEM=="tty",ENV{ID_PATH}=="platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.1:1.0",SYMLINK+="ttyUSB01" SUBSYSTEM=="tty",ENV{ID_PATH}=="platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.2:1.0",SYMLINK+="ttyUSB02" SUBSYSTEM=="tty",ENV{ID_PATH}=="platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.3:1.0",SYMLINK+="ttyUSB03" SUBSYSTEM=="tty",ENV{ID_PATH}=="platform-fd500000.pcie-pci-0000:01:00.0-usb-0:1.4:1.0",SYMLINK+="ttyUSB04" The result when listing the USB ports on my RPi4 is: $ ll /dev/ttyU* crw-rw---- 1 root dialout 188, 0 Oct 6 12:33 /dev/ttyUSB0 lrwxrwxrwx 1 root root 7 Sep 24 10:09 /dev/ttyUSB01 -> ttyUSB0 lrwxrwxrwx 1 root root 7 Oct 6 12:29 /dev/ttyUSB03 -> ttyUSB1 crw-rw---- 1 root dialout 188, 1 Oct 6 15:08 /dev/ttyUSB1 As you can see here ttyUSB01 is the first plugged in adapter and ttyUSB03 is the second. Had I reversed the order of plugging them the base name would have changed but the proper one could be accessed via the socket based name. But these symlinks do not show up in the command above since the group of these symlinks is not set to dialout, it is root... And to get them into the system one has to edit the rules file... This in itself is a non-obvious task since one has to find the hardware ID of each USB port in the system... -- Bo Berglund Developer in Sweden -- _______________________________________________ lazarus mailing list lazarus@lists.lazarus-ide.org https://lists.lazarus-ide.org/listinfo/lazarus
