Tech Briefs Magazine - December 2023 - MD-8

PLC or machine controller
Remote I/O modules
CPX-AP-I
Bus interface
CPX-AP-A
Pneumatic valve terminals
connects to the bus interface, and
scans the bus interface to identify the
full system of remote modules from
within the PLC software.
Another benefit of using a bus inIndustrial
Ethernet
network:
Proximity
sensors
Inductive sensors
Stack lights
Pneumatic cylinders, position sensors
Linear motion control
Rotary motion control
Layout of automation components in the same machine using a different approach to remote I/O modules and
valve terminals. Each module and terminal connect to the bus interface, which acts as gateway to the industrial
Ethernet network. This system requires just one point of integration into the PLC program and just one available
network address for the same level of performance and functionality. (Image: Festo Corporation)
backplane communications, meaning
they are fast, have low overhead, and are
transparent to the user.
The bus interface is the only device
that connects directly to the industrial
Ethernet network. This means just one
set of integration tools is required, which
includes a device library in the case of
PROFINET and EtherCAT networks, or a
data structure in the case of EtherNet/IP
and Modbus TCP. A downloadable software
configuration tool is available, but
the bus interface also provides a webserver
so that no software download is
required. The webserver allows the controls
engineer to directly access system
information, including system health and
diagnostic information for the remote
modules and terminals connected to the
bus interface.
In the case of EtherNet/IP, the webserver
allows a system-specific data structure
to be downloaded directly from the
bus interface. The data structure is imported
into the PLC code complete with
correct data types, data lengths, and human-readable
tags for all inputs and outputs
in the system. In the case of
PROFINET and EtherCAT networks, the
user installs the available device library,
terface is the reduction in the number
of network addresses required for the
various remote I/O modules and valve
terminals on the machine. The bus
interface requires one network address,
regardless of the number of remote
modules and terminals connected
to it. If there is just one module/terminal
or 50 of them (some
systems can support up to 80 devices
per bus interface), only one network
address is required.
Compare a hypothetical machine
with four remote I/O modules - a
mix of digital and analog input modules
and three remote valve terminals
- each controlling a group of pneumatic
actuators. In the conventional
decentralized approach, this machine
would require seven network addresses,
one for each of the modules and terminals.
In the new approach, only one network
address is required for the bus interface,
which connects to the network via its
industrial Ethernet connection (M12,
D-coded) and to the seven total modules
and valve terminals via physical backplane
connections or cables.
The speed of communications used
between the bus interface and the remote
modules and terminals is such that
there is no bottleneck in data rates between
the PLC and the field-level sensors
and actuators. The same amount of data
passes between them, including cyclic
process data and acyclic configuration
data. Diagnostic data is provided for
every device, which can be applied to
predictive maintenance programs and
machine learning applications.
Additional Benefits for Machine
Builders
System implementations that connect
fewer devices to the Ethernet network are
With the Festo Automation Platform (AP), a decentralized remote I/O and valve system based on the bus interface
concept, I/O modules and valve terminals can be connected via physical backplane (left) or via cable
(right). (Image: Festo Corporation)
8
easier to switch from one industrial protocol
to another. This is particularly useful
for machine builders who provide
solutions to a range of end-use customers.
Many end users standardize on a
particular protocol with several to choose
from, including EtherNet/IP, PROFINET,
EtherCAT, and Modbus TCP. A machine
builder can provide a solution to an end
user of EtherNet/IP one day and a simiMotion
Design, December 2023

Tech Briefs Magazine - December 2023

Table of Contents for the Digital Edition of Tech Briefs Magazine - December 2023