USB Kits

The USB serial hardware gives you a variety of solutions for serial communication. The USB-232 hardware works with the RS-232 interface standard, and the USB-485 hardware works with the RS-422 and RS-485 interface standards. 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.

Additionally, the USB serial hardware is available in one-port, two-port, and four-port versions. All versions use DB-9 connectors. Throughout this help file, USB serial hardware refers to all versions of the USB serial hardware.

The USB-232 two and four-port hardware supports three hardware transceiver modes supporting both DTE and DCE configurations. For more information about transceiver control modes, refer to USB-232 Transceiver Modes.

The RS-485 hardware supports 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. In addition, the USB-485 hardware supports programmatic control of the bias resistors. For more information, refer to USB-485 Programmatically Controlled Bias Resistors.

All USB 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) and USB buffers to reduce susceptibility to system 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.