ExpressCard Kits

The ExpressCard serial hardware gives you a variety of solutions for serial communication. The ExpressCard-8420 interface works with the RS-232 protocol, and the ExpressCard-8421 interface works with the RS-422 and RS-485 protocols. You can use the RS-232 ports for serial communication up to distances of 50 ft. You can connect the RS-485 ports to up to 31 devices using serial cable lengths up to 4,000 ft.

The ExpressCard-8420 and ExpressCard-8421 are available with two ports. All ExpressCard cards include cables for each port that terminates in a standard DB-9 connector. Throughout this help file, ExpressCard serial interfaces refers to all versions of the interfaces.

The RS-232 ports are DTE. In the RS-232 specification, Data Terminal Equipment (DTE) and Data Communications Equipment (DCE) refer to the types of equipment on either end of a serial connection. In general, DTE and DCE refer to computer equipment and modems, respectively. For more information about cabling a RS-232 port to other devices, refer to RS-232 DTE vs. DCE.

The RS-485 ports support four hardware transceiver control modes for reliable communication with two and four-wire devices. For more information about transceiver control modes, refer to RS-485 Transceiver Control.

All ExpressCard serial hardware uses standard 16550-compatible UARTs (Universal Asynchronous Receiver/Transmitters) for complete compatibility with standard PC COM ports. The serial hardware contains FIFO (First-In-First-Out) buffers to reduce susceptibility to interrupt latency for faster transmission rates. Full Plug and Play compatibility allows switchless configuration and installation. For more information about the serial hardware specifications and operating conditions, refer to the NI Serial Hardware Guide.

ExpressCard Board Names and Descriptions

ExpressCard Board Name	Description
ExpressCard-8420	RS-232 two port
ExpressCard-8421	RS-485 two port