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.


The Emerald-MM-8Plus is compatible with Windows 98/NT/2000/XP and Linux. If using Exar's default Vendor and Device ID, you can use Exar's module driver for Linux kernels 2.4.x and Linux kernels 2.6.1-2.6.7. Linux kernels 2.6.8 and newer have support in the kernel for the XR17x15x PCI UARTs. See the "8250_pci.c" in the kernel. If using your own Vendor and Device ID, you can use the module driver available from Exar after you modify the Vendor and Device ID accordingly in the module driver.


Interface8x RS-232, RS-422 or RS-485 (local and no echo) ports
Protocol Configuration: Jumpers
Software Configuration: Plug and Play
5, 6, 7, or 8 data bits; Even, odd, or no parity
Short circuit protection: Continuous, all outputs
RS-232Input impedance: 3KOhm minimum
Input voltage swing: ±30V maximum
Output voltage swing: ±5V min, ±7V typical
RS-422/485Differential: -0.2V min, +0.2V max input threshold
Input impedance: 12KOhm minimum
Input current: +1.0mA max (VIN = 12V), -0.8mA max (VIN = -7V)
Differential output voltage: 2.0V min (RL = 50 Ohm)
High/low states differential output voltage symmetry: 0.2V maximum
Data RatesUp to 1.8432Mbps
Address/IRQPlug and Play
OtherDigital I/O
• 8 individually programmable lines
• Input voltage: Logic 0: -0.3V min, 0.8V max, logic 1: 2.0V min, 5.3V max
• Output voltage: 0: 6mA max, 1: -4mA max

Termination Jumper: Selectable 120?
Connector(s)2 40-position (2x20) .025" square pin header on .1" centers;
Headers mate with standard ribbon cable (IDC) connectors


ExpansionStandard 16 bit PC/104 interface (passthough), 8-bit and 16-bit bus stack through headers are installed
Standard 32 bit PC/104-Plus interface
PCI bus VIO: Can be 3.3V or 5V
Electrical+5VDC ±10%
160mA typical consumption, all outputs unloaded
MechanicalWidth: 96 mm x 90 mm, 3.55" x 3.775"
Conformal CoatingOn request
SoftwareWindows 98/NT/2000/XP and Linux
TemperatureTemperature range (operation): -40°C to +85°C
Temperature range (storage): -40°C to +85°C
Humidity5% to 95% noncondensing
Weight3.1oz (87.9g)
Warranty1 Year



Emerald-MM-8PLUS 8 RS-232/422/485 Serial Ports PC/104-Plus Module
4 DB9M to 1 IDC40, 18 inches (for Hercules and EMM-8) (uses 2)
Order OnlineDSC Emerald-MM-8PLUS - Order Online
Recab UK
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