Emerald-MM-8Plus
PC/104-Plus 8-Port Multi-Protocol Serial Port Module

Description and Features
Two I/O headers are provided, with four serial ports 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-8Plus is based on the Exar XR17D158IV Octal UART. This device contains eight identical sets of registers, one set for each port. The registers are compatible with the standard PC serial port. Each port contains a 64-byte FIFO.
The Emerald-MM-8Plus has the following features.
• I/O connectors compatible with Emerald-MM-8P (two connectors, 40 pins, four ports per connector).
• Eight serial ports based on Exar XR17D158IV Octal UART with 64-byte FIFOs.
• RS-232, RS-422, RS-485, and TTL interfaces supported: RS-232/422/485 jumper selectable; TTL available as
a custom assembly configuration.
• Baud rates to 921.6Kbps in RS-232 or TTL mode, 1.8432Mbps in RS-422/RS-485 modes.
• Jumper-selected protocol and line termination.
• EEPROM storage of configuration data for instant availability on power-up.
• I/O lines are short circuit protected.
• Eight digital I/O lines with 5V logic.
• LED connected to digital I/O line 0.
• Programmable counter/timer with selectable clock source.
• Dual 40-pin I/O headers, 4 ports per header.
• +5V only operation.
• Extended temperature (-40°C to +85°C) operation.
• PC/104-Plus form factor.
• Stackthrough PC/104 and PC/104-Plus connectors installed.
Refer to the Exar XR17D158IV datasheet, listed in the Additional Information section of this document, for detailed information about using the UART, DIO and EEPROM functionality with the PC/104-Plus bus.