National Instruments PCI-232/4 用户手册

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The hardware issues a transmit empty interrupt when the number of 
characters in the transmit FIFO falls below the trigger level. Also, the 
hardware issues a receive full interrupt when the number of characters in 
the receive FIFO rises above the trigger level. For more information on 
FIFO buffers, refer to your PCI serial getting started manual.

Enter the following to set the receive FIFO trigger level to 56 and the 
transmit trigger level to 32 for 

/dev/ttyS5

:

linux PCI-SERIAL# ./FIFOtrigger 5 0x80 0x20

Every serial port has an associated 

struct termios

. By using this 

struct termios

 in a program, you can set the baud rate, character size 

(number of data bits), parity, control characters, flow control, and input and 
output mode. For more information about the termios structure, refer to the 

termios man page

. To view the 

termios man page

, enter the 

following:

linux# man termios

To configure your serial port, use a program segment similar to the 

termios_program.c

 in your 

PCI-SERIAL

 directory.

Table 1.  tx_trigger Values

8

0x00

16

0x10

32

0x20

56

0x30

Table 2.  rx_trigger Values

8

0x00

16

0x40

56

0x80

60

0xC0