Specifications

21PLCs
Overview
Digital I/Os communicate digitally to
industrial sensors and actuators. The
sensors and actuators are located in
the eld and, thus, are represented on
the lowest level of the control system’s
hierarchy. In contrast to analog I/O
modules, digital I/O modules send
or receive information that is either
1-bit (binary) information or quantized
values. The information ow can
be unidirectional or bidirectional,
depending on the interface type.
The most signicant advantage to
using digitized information is its
tolerance of noise. Consequently,
digital I/O functions allow longer
cable runs than analog signal cables.
Interface Types
Common digital interfaces are 24V
digital I/Os, which are traditionally
unidirectional and based on two-, three-,
or four-wire cabling. A 24V digital I/O
provides both the 24V and ground
supplies to the sensor/actuator, as well
as one or two (unidirectional) data lines.
IO-Link
®
is a newer sensor/actuator
interface technology based on 24V
I/Os. In an IO-Link system, the data line
is bidirectional and supports data rates
up to 230kbps. The IO-Link point-to-
point interface connects one sensor or
actuator to one digital I/O port. With
intelligent and congurable sensors,
IO-Link enables remote conguration,
diagnostics, and monitoring of
the peripheral equipment.
Digital I/O Functions
TO/FROM
SENSORS,
ACTUATORS,
HMI
SWITCH
DEBOUNCER
VOLTAGE MONITORS
HOT-SWAP
CONTROLLER
POWER SUPPLY
DIGITAL INPUTS
IO-Link
RS-485
CompoNet
™
DIGITAL OUTPUTS
CONTROLLER
UART
CAN
WIRELESS
THERMAL
MANAGEMENT
POWERLINE
COMMUNICATIONS
COMPARATORS
= MAXIM SOLUTION
With an industrial digital I/O interface, 1-bit or quantized data flow to and from the sensors and actuators is easy.