HCPL-0720-500E Datasheet, PDF (12/18 Pages) AVAGO TECHNOLOGIES LIMITED – 40 ns Propagation Delay, CMOS Optocoupler

Digital Field Bus Communication Networks
To date, despite its many drawb­ acks, the 4 - 20 mA ana-
log current loop has been the most widely accepted
standard for implementing process control systems. In
today’s manufacturing environment, however, automat-
ed systems are expected to help manage the process,
not merely monitor it. With the advent of digital field bus
communication networks such as CC-Link, DeviceNet,
PROFIBUS, and Smart Distributed Systems (SDS), gone
are the days of constrained information. Controllers can
CONTROLLER
now receive multiple readings from field devices (sen-
sors, actuators, etc.) in addition to diagnostic informa-
tion.
The physical model for each of these digital field bus
communica­tion networks is very similar as shown in
Figure 15. Each includes one or more buses, an interface
unit, optical isolation, transceiver, and sensing and/or ac-
tuating devices.
BUS
INTERFACE
OPTICAL
ISOLATION
TRANSCEIVER
TRANSCEIVER
OPTICAL
ISOLATION
BUS
INTERFACE
TRANSCEIVER
OPTICAL
ISOLATION
BUS
INTERFACE
FIELD BUS
TRANSCEIVER
OPTICAL
ISOLATION
BUS
INTERFACE
DEVICE
CONFIGURATION
MOTOR
STARTER
Figure 15. Typical field bus communication physical model
XXXXXX
YYY
MOTOR
CONTROLLER
TRANSCEIVER
OPTICAL
ISOLATION
BUS
INTERFACE
SENSOR
12