Tech Briefs Magazine - August 2021 - 18

Communications Interfaces
Shared-Access Bus
Industrial Ethernet
Controller
Switch/
Router
Controller
Internet
(or Intranet)
Switch/
Router
Office Ethernet
Shared-access wiring systems are based on a bus topology, with multiple
devices sharing a common wiring backbone.
ordinary Ethernet networks. Industrial
Ethernet systems such as Profinet IRT,
EtherNet/IP, and Ethernet Powerlink
address this through modified protocol
stacks and special hardware that give
critical messages priority access to network
bandwidth. The special components
needed to achieve this can add to
system complexity and cost.
It should be noted that while Ethernet
offers a vision of an unlimited number
of devices and flexible topology options,
issues of system performance - especially
for real-time motion control applications
- can require design compromises
that reduce local traffic and provide
direct communications paths for
critical components.
IO-Link is a low-cost, easy-to-implement
communications system de -
signed to simplify connections be -
tween fieldbus or industrial Ethernet
networks and simple sensors or actuators
located on the factory floor. On
one side of an IO-Link master gateway
device is an interface to the plant-wide
network, while the other side has multiple
point-to-point connections to in -
dividual sensor devices.
The IO-Link interface for end de vices
is relatively simple, eliminating the need
18
Cov
Industrial Ethernet uses the same technical underpinnings as office Ethernet
but with enhancements that make it better suited to harsh factory conditions.
to support complex communications
protocols at the sensor/actuator level.
IO-Link supports a variety of data types
including measurement data, device
configuration instructions, and information
about operating condition parameters
such as temperature.
Wireless Communications
Wireless technologies enable communications
with mobile machinery (e.g.,
autonomous guided vehicles) or equipment
that must be relocated frequently.
Wi-Fi (IEEE 802.11) and Bluetooth are
widely used standards for short-range
wireless communications. Other standards
are available for longer-range communications,
although these may have
lower bit rates. Emerging 5G networks
promise high data rates and low latency.
Wireless communications can be less
reliable than wired connections in electrically
noisy environments and may not
be suitable for highly time-dependant
feedback signals. In the case of a warehouse
robot, for example, a wireless signal
can be used to instruct the machine
to retrieve material from a particular
location. How ever, sensors for steering,
speed control, and collision avoidance
would typically be hard-wired to the conwww.techbriefs.com
ToC
trol
system to ensure reliable, instantaneous
response.
Open Standards for
Compatibility
No single vendor can supply best-inclass
equipment for every part of a complex
automation system and suppliers
of industrial networking technologies
have moved from proprietary networking
systems towards supporting open
(vendor-neutral) interface and networking
standards. With these standards,
buyers of motion control equipment
can mix and match standards-certified
components from different vendors
with the expectation that everything
will work together.
Important industry standards organizations
include the Open Device Vendors
Association (www.odva.org), sponsors of
DeviceNet and Eth ernet/IP standards;
the CAN in Auto mation Association
(www.can-cia.org), sponsors of the CAN -
open protocols; and Profibus Nutzer -
organ isation (www.profibus.com), sponsors
of Profibus and Profinet interfaces.
This article was written by Christian Fell,
General Manager at FRABA Inc., Ham -
ilton, NJ. For more information, visit
http://info.hotims.com/79416-121.
Tech Briefs, August 2021
http://www.odva.org http://www.can-cia.org http://info.hotims.com/79416-121 http://www.techbriefs.com http://www.abpi.net/ntbpdfclicks/l.php?202108MDNAV
Tech Briefs Magazine - August 2021

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