Access PCI-DIO-24D(H) - Manual (Page 5)

Manual PCI-DIO-24DH 5
Chapter 1: Introduction
Features
• 24 Bits of Digital Input/Output.
• All 24 I/O Lines Buffered on the Card.
• I/O Buffers Can Be Tri-stated under Program Control.
• Four and Eight Bit Ports Independently Selectable for I/O.
• Pull-Ups on I/O Lines. Pull Down resistors may be installed at the factory (**per port 8 bit**)
• Resettable fused +5V Supply Available to the User.
• "H" version compatible with Industry Standard I/O Racks.
• Three optional 82c54 type (**9 16-bit converters**) counters.
Applications
• Automatic Test Systems.
• Laboratory Automation.
• Robotics.
• Machine Control.
• Security Systems, Energy Management.
• Relay Monitoring and Control.
• Parallel Data Transfer to PC.
• Sensing Switch Closures or TTL, DTL, CMOS Logic.
• Driving Indicator Lights or Recorders.
Description
The card comes in two basic models. The difference between the two models is that I/O connections to
the D are via a standard 37-pin D-sub connector while I/O connections to the H are via a 50-pin
connector. The cards are 4.8 inches long and may be installed in any 5V PCI-bus slot in IBM and
compatible personal computers.
These cards provide 24 bits of parallel digital input/output on the PCI bus. These cards contain a type
8255-5 Programmable Peripheral Interface (PPI) chip. They can be programmed to accept inputs or to
provide outputs on three 8-bit ports designated Ports A, B, and C. Port C can be further divided into two
4-bit nibbles. The direction of each port is independent of other ports.
Each I/O line is buffered by a type 74ABT245B tristate buffer transceiver capable of sourcing 32 mA or
sinking 64mA. Pull-ups on the card assure that there are no erroneous outputs at power up until the card
is initialized by system software. The buffers are configured automatically by hardware logic for input or
output use according to direction assignment from a control register in the PPI. Further, if a jumper is
properly placed on the card, the tristate buffers may be enabled/disabled under program control. (See the
Option Selection section to follow.)