Emerald-MM-8Plus is a high performance multi-protocol serial communications board offering eight ports on a single PC/104-Plus module. Supporting baud rates up to 921.6K bps in RS-232 mode or 1.8432Mbps in RS422 or RS485 mode, each port can be individually selected for RS-232, RS-422, RS-485 or TTL level operation. Both local-echo and non-local-echo modes are supported for RS-485. Protocol selection is achieved via a jumper block for each of the eight ports. Line termination for RS-422/485 modes is also jumper-selectable.

Configuration of the Emerald-MM-8Plus is simple, using the built-in plug and play technology. For manual configuration, the base address for the board may be set in software, defining a 4K block of configuration space used to access the on-board registers. A single 32-bit read shows the detailed interrupt status for each of the eight ports. The PCI slot is defined through a jumper block. As with all Diamond Systems products, jumpers are paralleled with locations for zero ohm resistors to create a rugged, shock-and- vibration-resistant implementation.

Emerald-MM-8Plus is based on the Exar 17D158 octal UART IC. This device contains 8 4 identical sets of 16C55registers, one for each port, and is compatible with the standard PC serial port. Each port contains 64-byte transmit and receive FIFOs to support the high-speed data rates.

Emerald-MM-8Plus also offers 8 convenient digital I/O lines. The direction of each line is independently programmable. Finally, Emerald-MM-8Plus also offers a 16-bit programmable counter / timer with a configurable clock source.

Two I/O headers are provided, with four serial ports and four digital I/O lines on each header. The board operates on +5V only, eliminating the need for a +12V supply that is often required for serial port operation.