Page 18 - EngineerIt January 2021

AUTOMATION

Why Profinet is a great choice

for I/O networks

By Darrell Halterman, senior product manager of PACSystems controllers at Emerson’s machine automation
solutions business

he PROFINET industrial flexibility to choose any combination of best-of-class I/O systems. They can select
Ethernet communications panel or field-mountable versions of each device as required to fit the application,
Tprotocol was purpose-built to and can even source them from different suppliers, with high confidence in their
deliver inter-operability, high reliability and interoperability.
performance communications, high
availability architectures and advanced Uninterrupted communications
diagnostics to help with In much the same way as consumer-grade home networks, industrial-grade I/O
troubleshooting. These features help to systems can be connected with switches and cables in a star topology. However, the
minimise operational downtime and `always-on’ performance demand of automation often requires solutions more robust
enable designers to create robust and than those available using basic IT technology. PROFINET addresses these concerns
reliable industrial automation by providing various levels of redundancy, with the specific aim of providing
input/output (I/O) networks that are uninterrupted communications.
maintainable long-term. These I/O Using a ring network configuration, Media Redundancy Protocol (MRP) provides
networks are relied upon to enable communications recovery within a few milliseconds of networking loss due to a cable,
programmable logic controllers (PLCs), device or switch failure. These networks can be designed with external switches to
programmable automation controllers form a ring. Designs can be simplified for industrial controller and I/O systems by
(PACs) and industrial edge controllers incorporating on-board embedded multi-port switches within controllers and I/O
to perform deterministic control. devices, enabling a ring network to be created without the need for external switches.
Early industrial automation Controller redundancy is often needed in the most critical applications, which
protocols relied upon proprietary media requires PLCs, PACs or industrial edge controllers that can be installed in pairs on an
and components, partly to guarantee MRP ring. One controller is the primary and the second is the hot back-up, configured
performance. As industrial networking to take over seamlessly if the primary fails.
made the transition towards
commercial Ethernet technology, it Diagnostics
remained necessary to address the Should there be a problem with an industrial automation I/O system, operators and
always-on need for automation maintenance personnel need to know about it as soon as possible. This still applies to
systems while guaranteeing systems that have been configured with MRP and redundant controllers, because
performance. Here are some of the even though operation will continue unabated after a single failure, the system may
reasons why PROFINET is an ideal fit then be just one additional failure away from an outage. PROFINET provides
for industrial I/O networks.

Connectivity
Automation systems for industrial
machines and equipment rely on the
connection of controllers to hardwired
field devices such as sensors and
actuators via I/O modules. Controllers
also connect with more intelligent and
capable I/O devices, such as variable
frequency drives (VFDs) and smart
pneumatic solenoid manifolds. These
devices often have Ethernet
connectivity and can be located in a
protected control panel or installed
directly on equipment. Using an
industrial protocol such as
PROFINET, designers have the

EngineerIT | December 2020 / January 2021 | 16