Chapter5 ATSerial Hardware Installation, Verification, and Configuration
SerialHardware and Software for Win dows 5-18 ni.com
Use 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—one for the transmitter and one for thereceiver. The receiver
FIFOtrigger denotes the number of characters received in the FIFO before
thePC 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 receiveFIFO settings to
preventoverrun errors due to interrupt latency.
•Ifdata transfer sizes are small, selecting receive FIFO settings just
abovedata sizes can reduce efficiency, so select lower settings.
Note If you want your serial hardware ports to use the names COM1,COM2,COM3,or
COM4, refer to the Common Questions section of Appendix D, Troubleshooting and
Common Questions.
Windows NT
Installing the Microsoft PnP ISA Enabler Driver
Whenyou install an AT board, you must install the PnP ISA Enabler
Driver.
TheAT serial hardware is Plug and Play.Windows NT 4.0 does not support
Plug and Play.In order for Windows NT to detect and install the Plug and
Play hardware,you m ust install the PnP ISA Enabler driverincluded on
your WindowsNT 4.0 CD-ROM. Complete the following steps to install
the driver:
1. Locate the Pnpisa.inffile in the Drvlib\Pnpisa\X86 folder on
the WindowsNT 4.0 CD-ROM.
2. Right-click on the Pnpisa.inf file,then select Install on the menu
thatappears.
3. Restart the computer.