Real-time safety
May 1st 2008 Stewart Robinson of Pilz Automation Technology outlines the technology
underlying SafetyNET p, a safe real-time Ethernet protocol for industrial
communication
Current automation technology
requirements are reaching the limits
of the industrial fieldbus systems
that are currently popular. The time is
therefore right for suppliers to provide new
fieldbus systems that offer significantly
improved features.
Automation technology is moving away
from centralised control systems with
simple, bit-oriented sensors and actuators;
the trend is towards distributed systems
with more sophisticated sensors and
actuators that incorporate an everincreasing
amount of onboard preprocessing.
The communication
requirements of systems are consequently
moving away from the currently common
master-slave bit transfer arrangement to
networks capable of transferring
commands and requests between
intelligent master systems.
Ethernet is a central, widely available and
well known communication medium that is
capable of being used for complex systems
at reasonable prices. If automation
technology takes advantage of Ethernet, the
potential for innovation is enormous.
However, there is a need to simplify Ethernet
installation and configuration, as current
commercial-grade Ethernet systems are still
quite complex and difficult to work with
compared to industrial fieldbus systems.
Machine productivity requirements are
driving a reduction in machine cycle times.
Automated system performance must
therefore be sufficient to cater for such
reduced cycle times, which, in turn,
requires modern fieldbus systems to be
capable of realising significantly shorter
cycle times than current systems can
provide.
SafetyNET p is a modern Ethernetbased
industrial fieldbus system that has
been developed in response to the new
challenges in automation technology. It
satisfies users' requirements while still
being as easy to install as the currently
available industrial fieldbus systems.
In order to meet the various industrial
requirements, SafetyNET p supports two
types of communication. The SafetyNET p
RTFL format is optimised for extremely fast
communication in highly dynamic
applications. The RTFN format also
provides the ability to communicate via
any Ethernet network. Both versions are
compatible with each other and may be
used separately or in combination.
SafetyNET p demonstrates that it is
possible to meet the user requirements of
an open, safe and deterministic real-time
Ethernet network. The real-time
performance, with scan times of 62.5us for
the RTFL version, is around 20 times faster
than most other industrial Ethernet
versions. It is open for any type of Ethernet
traffic, even for data traffic from other
industrial Ethernet versions.
Extremely versatile connection
technology enables a SafetyNET p
network to have a linear, tree or star
structure. The capability for structures and
subscribers to be changed during
operation is unrivalled.
To ensure that the system is open and
widely propagated, integration is being
supported by Safety Network International
eV. This organisation offers its affiliated
member companies product-neutral
integration utilities and development
support.
Please contact Pilz to request more
information about SafetyNET p. More articles from Pilz Automation Technology: | 
