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Products   >   Services   >   End-of-Life Products   >   Emerald-MM-DIO 4-Port Serial PC/104 Module
4 RS-232 serial ports
Flexible address and interrupt selection
Full interrupt sharing capability
Interrupt status register for Windows NT
Dual 20-pin I/O headers (2 ports per header) for serial ports
48 digital I/O lines
Edge detection capability on digital I/O
+5V only power supply
Two boards in one saves space and lowers cost
See Emerald-MM-DIO 4-Port Serial PC/104 Module Technical Resources
Request Product information
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Emerald-MM-DIO Datasheet
(.pdf, 124.4 kb)
Emerald-MM-DIO Manual v3.12
(.pdf, 452.6 kb)
Emerald-MM-DIO Example Programs for UD 5.91
(.zip, 311.1 kb)
Universal Driver Software

Emerald-MM-DIO 4-Port Serial PC/104 Module

4 - Port RS-232 + 48 Digital I/O PC/104 Module Extended Temperature

Emerald-MM-DIO 4-Port Serial PC/104 Module
click for a larger image
Edge Detection Feature
Interrupt Status Register
Interrupt Sharing
I/O Headers
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For users who need a higher level of integration than our standard products deliver, we offer this two-in-one board with 4 RS-232 serial ports, 48 digital I/O lines, and extended temperature operation.

Each serial port provides the standard set of PC serial port signals. The ST16C554 quad UART chip on board contains a 16-byte FIFO for each port and supports data rates of up to 115kbps. Interrupt sharing is fully supported among the four serial ports, and an interrupt status register enables the board to operate under Windows NT. Eight different address combinations are possible, and any of 11 different interrupt levels can be used.

The 48 digital I/O lines feature programmable direction on a line by line basis, and all lines have 10KOhms pull-up resistors. One group of 24 lines includes the additional feature of programmable edge detection. Both active line selection and edge polarity are programmable. Status registers indicate which, if any, lines have changed logic levels in the selected manner since the last status check. An interrupt can be generated on the PC/104 bus whenever the indicated activity occurs.

Edge Detection Feature

The 24 digital I/O lines on ports 0 - 2 have edge detection capability. Active lines and edge polarity (rising or falling edges) are selectable line by line. When a selected line changes in the selected direction, a corresponding bit is set in an edge detection register. The 24 bits in these detection registers can be read and cleared by software. They are also funneled into an interrupt circuit, so that interrupts can be generated on the PC/104 bus when a change of state occurs.

Interrupt Status Register

The interrupt status register indicates the status of each port's interrupt request line. This register is required for proper operation under Windows NT. The status register will operate regardless of whether interrupt sharing is enabled. If two or more ports are sharing the same interrupt level, the status register will still indicate the correct status of each port's interrupt request line.

Bit Definition
7 -
6 -
5 -
4 -
3 INT4
2 INT3
1 INT3
0 INT1

INT4-INT1 Status of interrupt request for each port:
0 no interrupt request active
1 interrupt request active

Interrupt Sharing

Each serial port requires an interrupt line for proper operation. Since there are a limited number of interrupts on the PC/104 bus, using multiple serial ports on a single computer can quickly become a problem. For this reason Emerald-MM-DIO fully supports interrupt sharing, using tristate bus drivers and a status register to indicate the interrupt status of each port. Any number of ports or boards can share the same interrupt level.

I/O Headers

Emerald-DIO contains four I/O headers: Two 20-pin I/O headers for the serial ports, with 2 ports per header, and two 50-pin headers for the digital I/O.

RS-232 Mode

This pinout applies to ports 1 through 4. Signal numbering is shown for ports 1 and 2.

DCD 1 1 2 DSR 1
RXD 1 3 4 RTS 1
TXD 1 5 6 CTS 1
DTR 1 7 8 RI 1
GND 9 10 N/C
DCD 2 11 12 DSR 2
RXD 2 13 14 RTS 2
TXD 2 15 16 CTS 2
DTR 2 17 18 RI 2
GND 19 20 N/C

Digital I/O

Digital I/O (Digital I/O ports 0, 1, 2 shown; same pinout used for ports 3, 4 and 5).

Port 2 Bit 7 1 2 GND
Port 2 Bit 6 3 4 GND
Port 2 Bit 5 5 6 GND
Port 2 Bit 4 7 8 GND
Port 2 Bit 3 9 10 GND
Port 2 Bit 2 11 12 GND
Port 2 Bit 1 13 14 GND
Port 2 Bit 0 15 16 GND
Port 1 Bit 7 17 18 GND
Port 1 Bit 6 19 20 GND
Port 1 Bit 5 21 22 GND
Port 1 Bit 4 23 24 GND
Port 1 Bit 3 25 26 GND
Port 1 Bit 2 27 28 GND
Port 1 Bit 1 29 30 GND
Port 1 Bit 0 31 32 GND
Port 0 Bit 7 33 34 GND
Port 0 Bit 6 35 36 GND
Port 0 Bit 5 37 38 GND
Port 0 Bit 4 39 40 GND
Port 0 Bit 3 41 42 GND
Port 0 Bit 2 43 44 GND
Port 0 Bit 1 45 46 GND
Port 0 Bit 0 47 48 GND
+5V 49 50 GND


Serial Ports
Number of serial ports 4, RS-22
Maximum baud rate 115kbps
Communications parameters 5, 6, 7, or 8 data bits;
Even, odd, or no parity
Short circuit protection All outputs protected against continuous short circuit
Input impedance 3KΩ min
Input voltage swing ±30V max
Output voltage swing ±5V min, ±7V typical
Digital I/O
No. of lines 48
Direction Programmable bit by bit
Compatibility TTL/CMOS
Output current ±8mA over full spectrum of temperature range
I/O header .025" square pin header on .1" center;
Headers mate with standard ribbon cable (IDC) connectors
Serial ports 2 20-position (2x10) headers
Digital I/O 2 50-pin (2x25) headers
All I/O headers mate with standard ribbon cable (IDC) connectors
Dimensions 3.55" x 3.775"
Power supply +5VDC ±5%
Current consumption 100mA typical, all outputs unloaded
Operating temperature -40 to +85°C Extended
Operating humidity 5% to 95% noncondensing
PC/104 bus 8-bit and 16-bit bus headers are installed (16-bit header used for interrupt levels only)
Weight 3.2oz/91g

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Emerald-MM-DIO 4-Port Serial PC/104 Module
available models:
Emerald-MM 4-ch RS-232 + 48 Digital I/O w/ Edge Detect Extended Temperature
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VDC 2006 Platinum Vendor Award