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Chapter 1 Introduction
Serial Hardware and Software for Windows 1-6 ni.com
PCMCIA Kits
The serial hardware gives you a variety of solutions for serial
communications. The PCMCIA-232 interfaces work with the RS-232
protocols, and the PCMCIA-485 interfaces work with the RS-422 and
RS-485 protocols. You can use the PCMCIA-232 hardware for serial
communication up to distances of 50 ft.You can connect the PCMCIA-485
hardware with up to 31 devices using serial cable lengths up to 4,000 ft.
The PCMCIA-232 is available with one, two, or four ports. The
PCMCIA-485 is available in a one-port version or two-port version.
All PCMCIA cards come with cables for each port that terminates in a
standard DB-9 D-Sub connector. Throughout this manual, references to
PCMCIA serial interfaces generally refer to all versions of the interfaces.
The PCMCIA-485 interfaces support four hardware transceiver control
modes for reliable communication with two-wire and four-wire devices.
Refer to Chapter 6, Using Your Serial Hardware, for more information
about transceiver control modes.
All of the serial hardware uses standard 16550-compatible UARTs
(Universal Asynchronous Receiver/Transmitters) for 100 percent
compatibility with standard PC COM ports. The serial hardware contains
FIFOs (First-In-First-Out buffers) for reduced susceptibility to interrupt
latency and faster transmission rates. Full Plug and Play compatibility gives
you the convenience of switchless configuration and installation. Refer to
Appendix E, Specifications, for more information aboutthe serialhardware
specifications and operating conditions.
AT Kits
The serial hardware gives you a variety of solutions for serial
communications. The AT-232 boards work with the RS-232 protocols, and
the AT-485 boards work with the RS-422 and RS-485 protocols. You can
use the AT-232 hardware for serial communication up to distances of 50 ft.
You can connect the AT-485 hardware with up to 31 devices using serial
cable lengths up to 4,000 ft.
The AT boards are available in three different versions:
• Shared IRQ: All ports on the board share the same IRQ.
• Isolated: All ports on the board are isolated and share the same IRQ.