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Diamond Systems EMM-4M-XT

4-Port RS-232/422/485 Serial PC/104 Wide Temperature Module

Things Embedded are an official Diamond Systems USA distributor and can supply the EMERALD-MM-4M.


Serial I/O


Diamond Systems


Diamond Systems’ Emerald-MM PC/104 module gives you 4 serial ports operating at speeds up to 115kbps. In RS-232 mode, the full complement of standard PC serial port signals (8 signals + ground) are provided for each port and are grouped onto two 20-pin headers (2 ports per header). In RS-422 mode, Signals RX+, RX-, TX+, and TX- are provided, along with ground. In RS-485 mode, signals TX+/RX+ and TX-/RX- are provided, along with ground.

5V-only operation and -40 to +85C industrial operating temperature range are standard features. The industry-standard 16C554 UART is compatible with all popular embedded operating systems.

Flexible Configuration

Emerald-MM from Diamond Systems offers more interrupt level and I/O address options than other quad serial port modules. Therefore, integrating the board into your computer system is a simpler task. Eight different I/O address combinations and 10 different interrupt levels are available.

Interrupt Sharing

To help conserve ISA bus interrupts, any number of ports can share the same interrupt level. If you have two boards in one system, both boards can share the same interrupt level as well. An interrupt status register is provided to indicate the status of each serial port’s interrupt request signal.

Interrupt Configuration

Interrupt levels are individually selectable for each port. The available interrupt levels are 2, 3, 4, 5, 6, 7, 10, 11, 12, and 15. In addition, a 1K Ohm pulldown resistor is provided for each port.

A single interrupt level can be shared by 2, 3, or 4 ports on one board and can even be shared by more than one board in the system. To enable interrupt sharing, set two or more interrupt level jumpers to the same level and pull out all but one pulldown resistor jumper.


Brand & Model Diamond Systems EMM-4M-XT
4-Port RS-232/422/485 Serial PC/104 Wide Temperature Module
Features Compact
Serial Ports
Number of ports 4
Protocols supported RS-232, RS-422, RS-485
Protocol selection Individual jumper selection for each port
Maximum baud rate 230.4kbps
Communication parameters 5, 6, 7, or 8 data bits; Even, odd, or no parity
Short circuit protection All outputs protected against continuous short circuit
RS-232 Protocol
Input impedance 3KΩ minimum
Input voltage swing ±30V maximum
Output voltage swing ±5V min, ±7V typical
RS-422, RS-485 Protocols
Differential -0.2V min, +0.2V max input threshold
Input impedance 12KΩ minimum
Input current +1.0µA max (Vin = 12V), -0.8µA max (VIN = -7V)
Differential output voltage 2.0V min (RL=50Ω)
High/low states differential output voltage symmetry 0.2V maximum
I/O Headers 2 20-position (2×10) .1″ pitch right-angle pin headers
Dimensions 3.55″ x 3.775″ / 90x96mm (not including I/O connector pins)
Power supply +5VDC ±10%
Current consumption 80mA typical, all outputs unloaded
PC/104 bus 8-bit and 16-bit bus headers are installed; 8-bit databus width
Weight 2.6oz/74g
MTBF 555,000 hrs
RoHS Compliant

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