WORLD OF INDUSTRIES 04/2019 (EN)

The DNA of the Industrial
Internet of Things
Single Pair Ethernet - or SPE for short - is currently one
of the mega-trends in industrial data transmission.
If you want to understand the applications and
advantages of reducing data cabling to a single wire
pair, you must learn about the history of Ethernet
and industrial automation.
AUTOMATION
As a non-standardized software protocol, Ethernet was developed
in the 1970s for the internal and locally limited transmission
of data packets in wired computer networks (LAN - Local Area
Network). The Institute of Electrical and Electronics Engineers
(IEEE) defined the software protocol and the physical layer - including
physical interfaces such as connectors and cables - in the
following two decades and laid the foundation for the modern Internet
with the introduction of various protocols such as 802.4 (Token
Bus), 802.5 (Token Ring) and finally 802.11 (WLAN).
Common language
Parallel to this, fieldbus technology developed in the 1980s, driven
by the increased use of electrical automation technology. The basic
idea was the same: Different communication participants should
communicate with each other in an orderly manner and in a common
system. However, the various fieldbus protocols, such as Interbus,
DeviceNet and Profibus, were not used for networking computers
at company level, but for serial or parallel connection of
sensors and actuators to the control and management level.
Ultimately, the parallel development of the two transmission
protocols established the form of the automation pyramid that is
still valid today. The highest levels represent locally limited computer
networks which are used for rough and detailed production
planning. The lower levels comprise the signal, data and power
transmission for recording, controlling and regulating the physical
production process (Fig. 1).
The shape of the pyramid resulted primarily from the hierarchical-logical
arrangement of the different levels. However, it also rep-
Author: Dipl.-Wirt.-Ing. Verena Neuhaus, Manager Product Marketing
Data Connectors, Phoenix Contact GmbH & Co. KG, Blomberg, Germany
resents the previously valid framework conditions for industrial
data transmission: High transmission rates and short distances via
Ethernet, low transmission rates and long distances via fieldbus.
Turned upside down
So why this digression? Industrial Ethernet and especially Single
Pair Ethernet are turning this automation pyramid upside down.
With the development of Ethernet-based protocols such as Ether-
Net/IP, Profinet or EtherCAT, real-time data transmission from the
company level to the field level was introduced.
The physical interfaces became more powerful, but also more
complex in electrical terms, since data transmission had to be protected
from interference such as dirt, vibrations and electromagnetic
radiation. Manufacturers of connection technology therefore
developed special, IP6x-protected Ethernet interfaces to meet these
increased requirements at the field level. For the top of the automation
pyramid - the enterprise and operational level - IP20 solutions
were still sufficient.
Data transmission to the second power
So far, standardization efforts have been limited to ever higher data
rates and higher demands on cabling technology. These requirements
were defined by ever higher performance classes in copperbased
cabling - the Categories.
The Single Pair Ethernet does not again define higher bandwidths
or transmission distances, but forms the normative framework for
reduced cabling to suit the application. The IEC 63171-2 (IP20) and
IEC 63171-5 (IP67) standards focus on lower transmission rates of
10 to 100 Mbps. The data cabling with only one pair of wires nevertheless
enables transmission distances of up to 1000 meters. Thus,
for the first time, SPE allows areas of application and applications
that conventional Ethernet has not allowed to date, for example in
28 WORLD OF INDUSTRIES 2019