Com Port Number; Transceiver Mode; Fifo Enabled; Fifo Buffers - National Instruments PCMCIA-232 Getting Started

COM Port Number

Transceiver Mode

FIFO Enabled

FIFO Buffers

Resources

© National Instruments Corporation
You can use the COM Port Number control to change the COMx name of
the port selected.
The transceiver mode selection shows the transceiver mode in use, and
applies only to PCMCIA-485 cards. Refer to Chapter 4,
Hardware, for more information about transceiver modes. If you use
two-wire TXRDY mode, FIFOs must be enabled.
You can use the FIFO Enabled control to enable or disable the FIFO
buffers on the serial port. FIFO buffers are present on the
16550-compatible UARTs—one for the transmitter and one for the
receiver.
The FIFO buffer control is available by clicking on the Advanced button
on the Port Settings tab. FIFO buffers are present on the 16550-compatible
UARTs—one for the transmitter and one for the receiver. The receive FIFO
trigger denotes 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
interrupted to write the data. Consider the following points when selecting
FIFO settings:
• You can select larger FIFO settings to reduce the number of interrupts
and therefore minimize system overhead.
• If transfer rates are high, you can lower receive FIFO settings to reduce
the number of interrupts and therefore prevent overrun errors due to
interrupt latency.
• If data transfer sizes are small, selecting receive FIFO settings just
above data sizes can reduce efficiency, so select lower settings.
Click on the Resources button to display the resource configuration dialog
box for the port. For more information on resource configuration, refer to
the next section, Resource Settings.
3-3
Chapter 3 Configuration
Using Your Serial
PCMCIA Serial for Windows NT