PIPRS8

8-Port RS-232/RS-422/RS-485 PC/104 Module

The PIPRS8 PC/104 module (Emerald-MM-8) gives you 8 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. 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. Ports are grouped 4 per 40-pin I/O header. Ports 1-4 are on the right, and ports 5-8 are on the left.

Two 16C554 quad serial port ICs are used for the serial ports. This chip supports data transfer rates up to 115kbps and contains a 16-byte programmable FIFO buffer for each port to minimize processor overhead.

All serial port address and interrupt level settings may be done in software. On power up, the serial ports are disabled. After programming the address and interrupt settings, the ports are enabled by setting a bit in an auxiliary control register. For applications that require the ports to be operating without user software intervention, the board provides 4 different hardware configurations.

Interrupt levels are individually programmable 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 and is selected with a jumper. Any number of ports can share the same interrupt level. And 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. This register is especially useful in Windows NT.

The PIPRS8 has 8 programmable digital I/O lines. Each line can be independently programmed for input or output.

Another distinguishing feature of th PIPRS8 is its low-power +5V only operation. This board needs absolutely no +12V or -12V to operate. Extended temperature operation (-40 to +85°C) is also standard.

Technical Features

Serial Ports
Number of serial ports	8
Protocol	RS-232, RS-422, and/or RS-485
Maximum baud rate	115Kbaud
Communications parameters	5, 6, 7, or 8 data bits; Even, odd, or no parity
Base address options	Programmable
Interrupt level options	Programmable; select from levels 2 (9), 3, 4, 5, 6, 7, 10, 11, 12, 15
RS-232 Characteristics:
Input voltage swing	±30V maximum
Input thresholds
Logic 0:	0.8V min
Logic 1:	2.4V max
Input impedance	3KΩ minimum
Output voltage swing	±5V min, ±7V typical
Output resistance	300Ω minimum
RS-422/RS-485 Characteristics:
Differential input threshold	-0.2V min, +0.2V max
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 max differential
General
Short circuit protection	All outputs protected against continuous short circuit
I/O header	2 40-position (2x10) .025" square pin header on .1" centers; Headers mate with standard ribbon cable (IDC) connectors
Dimensions	3.55" x 3.775"
Power supply	+5VDC ±10%
Current consumption	80mA typical, all outputs open
Operating temperature	-40 to +85°C standard, all versions
Operating humidity	5% to 95% noncondensing
PC/104 bus	8-bit and 16-bit bus headers are used (16-bit header is used for interrupt levels only)

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