PCI Quad 422/485 Card
Chapter 2 Hardware Configration
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Chapter 2 Hardware
Configration
Introduction
This chapter details the specifications of the PCI quad RS422/485 card and
explains how to configure the RS485 Multiplex jumpers present on both cards.
These half-sized cards will work happily in any PCI 2.0 or greater compliant PC
compatible.
Card Features.
½ Four independent 9 pin D RS422/485 Serial ports.
½ Reliable communications up to 4000 feet, 1.2 Kilometres.
½ 16950 FIFO provides 128-byte input and 128-byte output buffer on each
port.
½ Maximum baud rate of 912600 Baud (1 Megabaud).
½ Word length of 5, 6, 7 or 8 bits.
½ Even, Odd, None, Mark or Space parity options.
½ 1 start bit always sent.
½ 1, (1.5 for 5-bit data word length), or 2 stop bits.
½ TXD, RXD, RTS, and CTS signals.
½ RS485 TXD/RXD multiplex selectable by jumpers: - either FULL
DUPLEX or HALF-DUPLEX.
½ Fully double buffered for reliable asynchronous operation.
½ High-speed integrated circuitry ensures operation with fast PC’s e.g. 800
MHz Pentium II WITHOUT extra wait states.
½ Autogating low level RS485 half duplex (2 wire) control
Clock Input:
60.00mHz
Drivers:
SN75174
High Level Voltage:
3.7V typical at 33mA source
Low Level Voltage:
1.1V typical at 33mA source
High Level Current:
-60mA max.
Low Level Current:
60mA max.
Receivers:
SN75175.
Difftial I/P threshold:
200mV max.
Hysteresis:
50mVolt typical.
Input Impedance:
>12K Ohm without terminators.
