This USB board is an ideal solution for adding portable, easy-to-install digital I/O capabilities to any computer with a USB port. It is a high-speed USB 2.0 device, USB 3.0 and 1.1 compatible. The board is plug-and-play allowing quick connect/disconnect whenever you need additional I/O on your USB port. The board features 48 bits of TTL-compatible digital I/O with high-current capabilities. Each digital port can be programmed to accept inputs or to drive outputs in six 8-bit ports. Power is supplied to the card via the USB cable, or for higher source current capabilities, an external power option may be ordered. The I/O wiring connections are via two industry standard 50-pin connectors. For external circuits, fused +5VDC power is available at pin 49 of each I/O connector. The resettable fuse is rated at 0.5A. All I/O lines are buffered by a type 74ABT543A tristate buffer transceiver capable of sourcing 32 mA or sinking 64 mA. The buffers are configured under program control for input or output. Jumper selected resistors permit configuration of each 24-bit / 50-pin connector group for pull-up (to +5 VDC), pull-down (to ground) or floating depending on the application requirement. Pull-ups are useful for contact monitoring and assure that there are no erroneous outputs at power-up until the card is initialized by system software. The USB-DIO-48 is designed to be used in rugged industrial environments, with extended temperature available. The board is PC/104 sized (3.550 x 3.775 inches, 90mm x 96mm) for added flexibility in embedded applications and is small enough to fit nicely onto any desk or testing station. Unlike most USB digital I/O products which primarily use a human interface device (HID) driver, ACCES providesw an easy to use, Windows/Linux-based, custom function driver capable of updating all 48-bits approximately 4000 times per second.