Chapter2 PCISerial Hardware Installation, Verification, and Configuration
©NationalInstruments Corporation 2-17 SerialHardware and Software for Windows
Advanced Port Settings
To view or change the advanced port settings, click on the Advanced
button. Figure 2-8 shows the Advanced Port Settings dialog box.
Figure2-8. AdvancedPort Settings Dialog Box
The followingsections describe the advanced port setting options.
TransceiverMode
Thisfi eld shows the transceiver mode in use, and applies only to PCI-485
boards.For more information about transceiver m odes, refer to Chapter 6,
Using Your Serial Hardware.
Use FIFO Buffers
FIFOb uffers are present on the 16550-compatible UARTs—one for the
transmitterand one for the receiver. The Receive Buffer control sets the
numbero fc haractersreceived in the FIFO before the PC is interrupted to
read the data. The Transmit Buffer control sets the maximum number of
byteswritten to the FIFO in a block when the PC is interrupted to write the
data. When you configure FIFO settings, consider the following points:
•Youcan select larger FIFO buffer sizes to reduce the number of
interruptsyour PC r eceivesand therefore minimize system overhead.
•Ift ransfer rates are high, you can lower the Receive Buffer value to
preventoverrun errors due to interrupt latency.
•Ifyour data transfer sizes are small and your Receive Buffer value is
aboveyour data sizes, your system is less efficient. Therefore, set the
ReceiveBuffer value below your data sizes.