Emerald-MM-8P offers 8 multi-protocol serial ports on a single PC/104 module with complete software configurability. Each port can be individually selected for RS-232, RS-422, or RS-485 under software control. Both local-echo and non-local-echo modes are supported for RS-485. I/O addresses and interrupt levels are also programmable, with interrupt sharing available for any number of ports. Each port may further be enabled or disabled in software. All configuration data is stored in an on-board EEPROM that is loaded automatically on power-up.
For applications where fixed addresses are desired, four groups of preset addresses are available with jumper settings that override the programmed settings. Line termination for RS-422/485 modes is also jumper-selectable. Emerald-MM-8P offers 8 convenient digital I/O lines. The direction of each line is independently programmable.
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.
Emerald-MM-8P is based on the 16C654 quad serial port IC. This device contains 4 identical sets of registers, 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 460.8kbps data rates. Model EMM-8P-XT is backward compatible with Diamond Systems EMM-8M-XT and EMM-8232-XT boards.