Sensoray 425 - Manual (Page 4)

Sensoray Model 425 Instruction Manual Page 2
Introduction
Block Diagram
The Sensoray model 425 is an ISAbus I/O card that
performs several functions commonly required in
embedded applications. On-board peripherals include:
• Programmable watchdog timer.
• 48 digital I/O channels. 16 channels have edge detection
and interrupt capability.
• 12-bit analog-to-digital converter with eight differential
input channels and resistor-programmed gain.
• Four 12-bit analog output channels.
• Three 24-bit counters optimized for interface to
incremental encoders.
The 425 is powered from the ISAbus 5-volt supply. No
auxiliary 12- or 15-volt supplies are required. Power
for linear circuitry is derived from an on-board DC-to-
DC converter. Low power CMOS circuitry is used
extensively to minimize power consumption and
enhance reliability.
The board occupies a 64-byte block of I/O addresses in
the ISAbus 16-bit I/O space. Programming shunts may
be installed to map the board to any 64-byte address
boundary.
Four headers are provided for connecting on-board
peripherals to external circuitry. Low profile vertical
headers are used to satisfy the tight clearances
mandated by modern high-density system designs.
8-channel
Diff Mux
L
O
C
A
L
B
U
S
IS
A
B
U
S
Digital I/O
Interface
3 x 24-bit
Counters Signal
Conditioning
System Bus
Decode
System
Data Bus
Buffer
12-bit D/A
12-bit D/A
12-bit D/A
12-bit D/A
12-bit A/D
Instrument
Amplifier
Watchdog
Timer
DC-to-DC
Converter
Analog I/O
Connector
Digital I/O
Connectors
Encoder
Connector
System
Interrupt
Control