Chapter5 ATSerial Hardware Installation, Verification, and Configuration
SerialHardware and Software for Win dows 5-24 ni.com
FIFO Enabled
Youcan use the FIFO Enabled control to enable or disabl e the
FIFObuffers on the serial port. FIFO buffers are present on the
16550-compatible UARTs—one for the transmitter and one for the
receiver.
FIFO Buffer Size
FIFOb uffers are present on the 16550-compatible UARTs—one for the
transmitterand one for the receiver. The receiver FIFO trigger denotes the
numbero fc haractersreceived in the FIFO before the PC is interrupted to
read the data. The transmit FIFO trigger denotes the maximum number of
byteswritten to the FIFO in a block when the PC is interrupted to write the
data. Consider the following points when selecting FIFO settings:
•Youcan select larger FIFO settings to reduce the number of interrupts
and thereforeminimize system overhead.
•Iftransfer rates are high, you can lower receive FIFO settings to reduce
the number of interrupts and therefore preventoverrun errors due to
interruptlatency.
•Ifdata transfer sizes are small, selecting receive FIFO settings just
abovedata sizes can reduce efficiency, so select lower settings.
ResourcesClickontheResourcesbuttonto displ ayt heresource config uration dialog
box for the port. For more information on resource configuration, refer to
the next section, Resource Settings.
Resource SettingsThefollowing sections explain the resource configuration options for each
serialinterface.