Chapter4 PCMCIASerial Hardware Installation, Verification, and Configuration
©NationalInstruments Corporation 4-21 SerialHardware and Software for Windows
FIFO Enabled
Youcan use the FIFO Enabled control to enable or disabl e the FIFO
bufferso nt he serial port. FIFO buffers are present on the
16550-compatible UARTs—one for the transmitter and one for the
receiver.
FIFO Buffers
The FIFO buffer control is available by clicking on the Advanced button
onthe Port Settings tab. FIFO buffers are present on the 16550-compati ble
UARTs—onefor the transmitter and one for the receiver. The receive FIFO
triggerdenotes the number of characters received in the FIFO before the PC
is interrupted to read the data. The transmit FIFO trigger denotes the
maximum number of bytes written to the FIFO in a block when the PC is
interruptedto write the data. Considerthe followi ng 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.
Resources
ClickontheResourcesbuttonto displ ayt heresource config uration dialog
box for the port. For more information on resource configuration, refer to
the next section, Resource Settings.