The USB-DIO-32 is an ideal solution for adding portable, easy-to-install digital I/O and counter capabilities to any computer with a USB port. The USB-DIO-32 is a USB 2.0 device, offering the highest speed available with the USB bus. It is fully compatible with both USB 1.1 and USB 2.0 ports. The unit is plug-and-play allowing quick connect or disconnect whenever you need additional I/O on your USB port. The USB-DIO-32 features 32 bits of TTL-compatible digital I/O with high-current capabilities and three optional 82C54 counters. Each digital port can be programmed to accept inputs or to drive outputs on four 8-bit ports, designated as port A, B, C, and D. Power is supplied to the unit via the USB cable or for higher current capabilities, external power may be used. The I/O wiring connections for USB-DIO-32 are via an industry standard 50-pin connector. For external circuits, fused +5VDC power is available at the connector. This resettable fuse is rated at 0.5A. All I/O lines are buffered by a type 74ABT245 tristate buffer transceiver capable of sinking 64 mA or sourcing 32 mA. The buffers are configured under program control for input or output. Pull-ups (to +5 VDC) or pull-downs (to ground) on the board allow for contact monitoring and assure that there are no erroneous outputs at power-up until the module is initialized by system software. Unlike most USB digital I/O products which primarily use a human interface device (HID) driver, ACCES offers an easy to use, Windows-based, custom function driver optimized for maximum data throughput. This approach exposes the full functionality of the hardware along with maximizing the advantage of using the high-speed USB 2.0 bus.