cpp - Process technology for the chemical industry 02.2018

APL – Extension of the IEEE 802.3cg standard
for use in the process automation
Architecture of an Ethernet network with APL
stamping, diagnostics and redundancy or
configuration of the system on the fly are
likewise possible. The industry’s characteristic
requirements have meanwhile also
been integrated into Profinet Tester, which
is used to carry out automated test runs at
accredited PI test laboratories by testing
both the interface functionality’s conformity
with the standard and the interoperability
of devices from multiple manufacturers.
New paths in hazardous areas
Every step was carried out in very close cooperation
with Namur. This will also apply
to the next set of tasks when field devices
with a Profinet interface are made accessible
to explosion-protected areas.
A little background information is needed
here: the use of Ethernet-based interfaces
with field devices for process instrumentation,
for example when explosion protection
requirements must be taken into account,
has its limitations. Apart from explosion
protection, the process industry also
needs two-wire communication. Segment
lengths of up to 1000 m are necessary in
large-scale chemical plants, and the process
sensors and actuators must be powered via
the two-wire connection parallel to communication
(loop power).
Since it makes sense to standardise this kind
of development, numerous representatives
from production, process and building
automation, as well as PHY manufacturers,
got together to initiate an IEEE call for interest
in July 2016. Just six months later, the
IEEE 802.3cg Task Force was ready to start
work on the specification of a new standard.
Based on this, ASIC manufacturers can now
develop an Ethernet PHY which is suitable
for an array of applications like the building,
manufacturing and process industries.
The special challenges of explosion protection
cannot be solved by IT experts, however.
This is why the three organisations –
FieldComm Group (FCG), ODVA and PI
(Profibus & Profinet International) – as well
as eleven industry partners of the APL (Advanced
Physical Layer) project have taken up
the gauntlet. On the one hand, an APL interface
with a very low energy requirement is
called for to enable intrinsically safe field
devices to be implemented. DEKRA EXAM is
presently collaborating on this. On the
other, this interface must be designed in
such a way that it is still economical. After
all, there are thousands upon thousands of
very simple temperature and pressure transmitters
at any chemical facility, so that expensive
interfaces simply aren’t realistic
here.
The APL project thus supports the current
work of the IEEE 802.3cg Task Force. The
framework for the new Ethernet standard
has already been defined: a data rate of
10 Mbps, simultaneous transmission and
reception via a two-wire line (full-duplex
communication) and optional an power
supply to connected terminal devices over
the same line (power over data line).
One central task of the APL project team is
to ensure the interoperability of APL components.
This includes specifying intrinsically
safe communication and supply as well
as the associated profiles, so that industrial
Ethernet field devices can be used in
hazardous areas up to Zone 0 or Class 1/
Division 1. Ensuring the conformity of
these devices, and hence their interoperability,
is likewise a top priority.
Working together with users
In the meantime, conformance and EMC
tests are already being defined, guidelines
for installation and test scenarios developed
and reference implementations addressed.
The APL team now needs to install a pilot as
soon as possible, so as to gain experience
with the new technology together with
users. The first certified APL devices are expected
in 2021.
www.cpp-net.com
Online search: cpp0218profibus
Hall11.0, Booth C43
AUTHOR:
DR. PETER WENZEL
Executive Director,
PI (Profibus & Profinet
International)
cpp 02-2018 67