NAME

       serport - Hardware driver for the digital I/O bits of the 8250 and 16550 serial port.

SYNOPSIS

       loadrt serport io=addr[,addr...]

       The  pin  numbers  refer  to  the 9-pin serial pinout.  Keep in mind that these ports generally use rs232
       voltages, not 0/5V signals.

       Specify the I/O address of the serial ports using the module parameter  io=addr[,addr...].   These  ports
       must not be in use by the kernel.  To free up the I/O ports after bootup, install setserial and execute a
       command like:
              sudo setserial /dev/ttyS0 uart none
       but  it is best to ensure that the serial port is never used or configured by the Linux kernel by setting
       a kernel commandline parameter or not loading the serial kernel module if it is a modularized driver.

FUNCTIONS

       serport.N.read

       serport.N.write

PINS

       serport.N.pin-1-in bit out
              Also called DCD (data carrier detect); pin 8 on the 25-pin serial pinout

       serport.N.pin-6-in bit out
              Also called DSR (data set ready); pin 6 on the 25-pin serial pinout

       serport.N.pin-8-in bit out
              Also called CTS (clear to send); pin 5 on the 25-pin serial pinout

       serport.N.pin-9-in bit out
              Also called RI (ring indicator); pin 22 on the 25-pin serial pinout

       serport.N.pin-1-in-not bit out
              Inverted version of pin-1-in

       serport.N.pin-6-in-not bit out
              Inverted version of pin-6-in

       serport.N.pin-8-in-not bit out
              Inverted version of pin-8-in

       serport.N.pin-9-in-not bit out
              Inverted version of pin-9-in

       serport.N.pin-3-out bit in
              Also called TX (transmit data); pin 2 on the 25-pin serial pinout

       serport.N.pin-4-out bit in
              Also called DTR (data terminal ready); pin 20 on the 25-pin serial pinout

       serport.N.pin-7-out bit in
              Also called RTS (request to send); pin 4 on the 25-pin serial pinout

PARAMETERS

       serport.N.pin-3-out-invert bit rw
       serport.N.pin-4-out-invert bit rw
       serport.N.pin-7-out-invert bit rw
       serport.N.ioaddr u32 r

LICENSE

       GPL

LinuxCNC Documentation                             2025-06-19                                         SERPORT(9)