I'm trying to read some data from the some serial ports (I need them to deal with a touch screen controller).What I'm basically doing is cat /dev/ttyS0 to see what does the serial give as output when touching the screen.I can cat (or screen or minicom) all 4 serial ports: /dev/ttyS0 to /dev/ttyS3, but for all of them I get no output, even when physically touching the screen.cat /dev/ttyS0 (or any other ttyS*) just hangs and gives no outputNeither cat /dev/ttyS0 | xxd gives output. I have to end cat with CTRL + Cscreen /dev/ttyS0 hangs with no output, same for the other ttyS*Useful infosOSCentOS 7ttyS in dmesg[root@centos-t1 ~]# dmesg | grep -i 'ttys'[    1.530144] 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A[    1.551401] 00:09: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A[    1.572603] 00:0a: ttyS2 at I/O 0x3e8 (irq = 10) is a 16550A[    1.593818] 00:0b: ttyS3 at I/O 0x2e8 (irq = 11) is a 16550AList of ttyS*[root@centos-t1 ~]# ls -la /dev/ttyS*crw-rw----. 1 root dialout 4, 64 29 dic 09.57 /dev/ttyS0crw-rw----. 1 root dialout 4, 65 29 dic 09.57 /dev/ttyS1crw-rw----. 1 root dialout 4, 66 29 dic 09.57 /dev/ttyS2crw-rw----. 1 root dialout 4, 67 29 dic 09.57 /dev/ttyS3setserial output[root@centos-t1 ~]# setserial -g /dev/ttyS*/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4/dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 3/dev/ttyS2, UART: 16550A, Port: 0x03e8, IRQ: 10/dev/ttyS3, UART: 16550A, Port: 0x02e8, IRQ: 11Kernel[root@centos-t1 ~]# uname -aLinux centos-t1 3.10.0-327.3.1.el7.x86_64 #1 SMP Wed Dec 9 14:09:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linuxlsusb[root@centos-t1 ~]# lsusbBus 003 Device 004: ID 05e3:0723 Genesys Logic, Inc. GL827L SD/MMC/MS Flash Card ReaderBus 003 Device 005: ID 058f:5608 Alcor Micro Corp. Bus 003 Device 006: ID 05e3:0608 Genesys Logic, Inc. HubBus 004 Device 002: ID 0403:6001 Future Technology Devices International, Ltd FT232 Serial (UART) ICBus 004 Device 003: ID 046d:c52b Logitech, Inc. Unifying ReceiverBus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hubBus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hubBus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hubBus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hubBus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hubBus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hubBus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hubPlease, note that PCI:004:002 is actually and RFID reader attached to the system. So it's not the serial I need to deal with - at the moment.Serial chipFintek F81866SystemEmbedded Touch Panel by Iei - AFL2-W10A-N28 Product page and DatasheetTouch screen controllerPenmount DMC9000 (attached via serial I suppose, since it isn't in the lsusb list)
Serial port - no output Penmount DMC9000
linux;io;serial port;minicom
I've managed to fix the problem.The serial port wasn't correctly detected beacause of an irq problem.Here is how I've fixed it:Switched from CentOS 7 to Debian 8.2 (jessie)With the following kernel (latest available): Linux debian-term1 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u1 (2015-12-14) x86_64 GNU/LinuxTemporarily enabled the touch screen via setserial /dev/ttyS3 irq 0 (this actually is the solution)Downloaded the Penmount drivers from this website, configured the penmount.ini to disable the noisy beep sound (via BeepType=0) and installed the driver module via ./install.shCalibrated the touchscreen via gCal 9 /etc/penmount/penmount.dat (had to start the X server, it's a GTK application, obviously)Made the changes permanent by adding a /usr/share/penmount/penmount.sh script containing the setserial command above and inserted it in /etc/init.d/lightdm start) section. I know it's dirty, but I'm planning to change it soon.Thank you guys for the help, now my Penmount DMC9000 works like a charm!