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equipment in the factory. This real plug-
and-work operation facilitates plant
layout modifications. Furthermore, HSR
supports the redundant IEEE 1588v2
submicrosecond
synchronization
protocol, which simplifies the
synchronization of the system to
perform precise reconstruction of
the sampled sensor data or the
implementation of control tasks. In
order to provide seamless redundancy,
each HSR node sends the Ethernet
frames through both directions of the
ring. This approach allows “hot” cable
or equipment plugging and unplugging.
Each node is in charge of forwarding
both frames, and the IEEE 1588v2
support corrects the residence and link
delay times to ensure timing accuracy
in the entire network. Thus, frame
hardware processing is mandatory
to ensure low and constant latency
times in every node. Indeed, the IEC
standard recom
mends a “cut-through” approach
for forwarding the frames in the
ring. To avoid circulating frames, for
unicast communications the node
that receives the frames is in charge
of removing them from the ring. For
multicast and broadcast traffic, the
sender removes the frames when it
sees them again in the redundant port.
Additional rules regarding circulating
frames (such as corrupted frames) are
applied to ensure network stability.
HSR, combined in many cases with the
Parallel Redundancy Protocol (PRP),
is the recommended High-Availability
Ethernet protocol in the standard for
the automation of one of the most
critical sectors worldwide: power sub
stations. Other sectors, such as
military and aerospace, are also
adopting these Layer 2 solutions.
Smart gateways provide hardware
switching from the Ethernet and
serial ports to the HSR infrastructure
ring. There are two smart gateways,
represented in the left and in the right
of Figure 3, that connect the HSR ring
with the Ethernet-based enterprise
network working as a redundancy box
(RedBox). Functionally, the access
point represented on the right is
optional, as it can be used to avoid
the single point of failure that would
appear in the case of a network using
only one RedBox. We recommend
implementing the dual-box setup in
cases where high availability is needed,
or when it is necessary to manage
PRP frames (IEC 62439-3 Clause 5)
in the critical nodes in the enterprise
network. Additionally, there are internal
networking ports in the gateway to the
processing elements of the SoC device.
In most cases, a “dumb” switching
approach is useless to join plant and
IT worlds. The heterogeneity in the
data and network formats makes
straightforward connections difficult.
What’s needed is a powerful integrated
processing system able to talk with
local, enterprise or cloud databases.
In addition, such a system would be
in charge of translating protocols,
managing HMI systems, supporting
MES systems and even running soft
PLCs for real-time control. But that is
not all. The customer also expects such
a system to perform complex sensor
data preprocessing and filtering in the
equipment, and of course, advanced
cybersecurity operations.
The cybersecurity requirements
in these kinds of advanced
manufacturing facilities vary widely.
Advanced security is necessary to
protect the status of the production
itself, avoiding any malicious or
accidental interruption generated
by any cyber infrastructure (device,
network, software or hardware). It
is also necessary to authenticate
users and devices that are accessing
information or any critical operation.
Furthermore, this information and
the control protocols need to be
protected in terms of authentication
and privacy, because factory networks
are connected to larger IT networks in
an enterprise and outside of it. These
challenges can only be addressed
with a layered cybersecurity approach
that takes into account each plant
implementation. A common element
in all the projects is the need to
support secure boot and storage
with encryption and authentication.
This feature will make credible the
implementation of secure software
and secure net
works. The trusted embedded system
is more and more difficult to protect
due to the increasing number of
devices and their heterogeneity. For
authentication and for networking
security, these systems can directly
Figure 2 – The CPPS-Gate40
smart gateway from SoC-e
48 l New-Tech Magazine Europe