Chapter 1: Introduction
Features
•
48 Bits of Digital Input/Output.
• Software
Controlled
Interrupt Generation.
•
All 48 I/O Lines are Buffered on the Board.
•
I/O Buffers Can Be Enabled/Disabled under Program Control.
•
Four and Eight Bit Ports Independently Selectable for I/O.
•
Pull-Ups on I/O Lines are standard, Pull-downs are an option.
•
+5V Supply Available to the User (fused, resettable).
•
Compatible with Industry Standard I/O Racks like Gordos, Opto-22, Potter & Brumfield, etc.
•
Counter/Timer 82C54, 3x16 bit (optional).
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
This board was designed for industrial applications and can be installed in a 16 bit or 8 bit PC/104 bus
socket. Each I/O line is buffered and capable of sourcing 32mA or sinking 64mA. The board contains
two Programmable Peripheral Interface (PPI) chips of type 82C55 to provide a computer interface to 48
I/O lines. There are three 8 bit ports: A, B, and C per PPI. Each 8 bit port can be configured by software
to function as either inputs or latched outputs. Port C can also be configured as four inputs and four
outputs. Pull-ups on the board assure that there are no erroneous outputs at power up. Pull-downs for
any port can be installed at the factory on request.
Also, bit C3 at each 24-bit Group can be used as an external interrupt to the computer. When bit C3
goes high (edge triggering), an interrupt may be requested. Interrupts from the ports are OR'ed
together. Interrupts are directed to levels #3 through #7 and #10 through #12 by jumper installation.
Jumpers allow interrupts from Port C bit 3 (either or both Groups) always, never, or controlled by Port C
bit 7.
Tristate I/O line buffers (74LS245) are configured automatically by hardware logic for input or output
according to direction assignment written to the control register in the PPI. Further, a jumper on the
board allows the tristate buffers to be enabled or disabled under program control. (See the Option
Selection section to follow.)
Manual 104-DIO-48E, 24E
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