Sensoray 421 - Manual (Page 4)

Page 2 Sensoray Model 421 Instruction Manual
Introduction
Block Diagram
Power for linear circuitry is derived from an on-
board DC-to-DC converter. Wherever possible, low
power CMOS circuitry is used to minimize system
power consumption and enhance reliability.
The board occupies a 32-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 32-byte
address boundary.
Four headers are provided for connecting on-board
peripherals to external circuitry. Right-angle headers
are used to satisfy the tight clearances mandated by
modern high-density system designs. All headers are
supplied with latches to ensure reliable operation in
vibrating environments.
The Sensoray model 421 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.
— 12-bit analog-to-digital converter with eight differential
input channels and resistor-programmed gain.
— Four 12-bit analog output channels.
— Three 16-bit counter channels optimized for interface to
incremental encoders.
The 421 is powered from the ISAbus 5-volt supply.
No auxilliary 12- or 15-volt supplies are required.
8-channel
Diff Mux
L
O
C
A
L
B
U
S
IS
A
B
U
S
Digital I/O
Interface
3 x 16-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