Keithley PIO-96, Инструкция по эксплуатации

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1-2 General Description PIO-96 User’s Manual
The board
The PIO-96 board is a 96-line parallel digital I/O interface board. The combined board and sup-
plied software installs and runs in any IBM PC-compatible computer that runs the Microsoft
Windows® 95/98/NT operating system (Pentium®-series processor recommended).
The PIO-96 board is built around four industry-standard Intel 8255, 24-bit, programmable
peripheral interface (PPI) adapter chips. Each 8255 includes the three TTL/CMOS-compatible
digital I/O ports PA, PB, and PC. The PA and PB ports are byte-wide (8 bits) and configurable as
inputs or outputs. The PC port is also byte-wide but can be divided into two separate 4-bit ports:
PC lower and PC upper (each of which can be set up as either inputs or outputs). The PIO-96
supports the full set of operating configurations of the 8255 PPI as set by its Control Register.
On power-up, or whenever the computer’s hardware-reset line is asserted, all ports are cleared
and set in a digital-input mode.
The PIO-96 uses 16 consecutive I/O addresses within the computer I/O address space (four
addresses for each 8255 chip). The base address of the PIO-96 board is set by a base address
switch. More than one PIO-96 may be installed in a single computer. However, each installed
PIO-96 uses 16 I/O addresses (base a0 through base a15), and no two boards
can use the same address.
The PIO-96 also includes a wait-state generator that insures a 300ns I/O cycle time, minimum,
as required by the 8255. If your computer does not require the wait-state generator, it can be dis-
abled by setting the wait-state jumper to the OFF position.
The computer power supplies p5V power through the I/O connectors for use in external
applications, such as the addition of pull-up resistors. The +5V supply may also be used to
power external accessories, as long as you observe the total-available-power limits of your com-
puter and ensure that each connector pin current is limited to less than 1A.
NOTE
Do not connect the +5V outputs to an ex5V supply.
I/O connections for each 8255 port use a 50-pin, 0.1-inch header connector. This configuration
assures maximum shielding and minimum cross-talk by placing a ground wire in the cable
between each I/O conductor. The mating connector socket is the 3M 3425-6050 (one required
for each 24-bit port), or you may purchase a ready made 24-inch cable with connectors on both
ends as Keithley part number CACC-2000. Longer cables are available by specifying Part
#
CACC-20NN, where NN is the number of feet added to the standard two-foot cable. Wiring
accessories are also available.
General areas of application for the PIO-96 include all parallel-digital I/O requirements, such as
communicating with peripherals, operating relays, reading switch inputs, etc.