Controls News 13
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Technology:
every cable less makes life that little bit easier
Saia® S-Link: operating principle
Saia-Burgess can also see the enormous potential
for optimization in the automation environment of
using a single cable for both power supply and com-
munication – and is presenting the perfect solu-
tion with the communication interface Saia® S-Link
(
Supply-Link).
In the Saia® S-Link, the data signal is modulated via
a carrier frequency on the power supply line. This
technology is also known as powerline communi-
cation. In contrast to the network communication
commonly used in the consumer market, which is
designed for 230 VAC supply lines, Saia® S-Link also
works with 24 VDC as well as the 24 VAC lines com-
monly found in building automation.
One of the two conductors is used as a reference
potential while the information is modulated onto
the other conductor with a fixed carrier frequency.
S-Link can therefore be used as a half-duplex com-
munication channel for single-master systems. If a
protocol is used which contains a ‘token passing’
mechanism, for example, a multi-master bus system
can also be developed. No additional control lines
are required.
Saia
®
S-Link
lets energy and data flow along
the same line
In vehicle construction, the general trend is to use the power supply lines for data
transfer as well. The main reason for doing this in the automotive sector is to reduce
vehicle weight. The size of the cable harnesses and the complexity during trouble-
shooting also play a role.
Authors: Kostas Kafandaris/Andreas Pfäffli
Easy to install and user-friendly
Saia® S-Link enables data communication via a de-
vice’s two conductors of the power supply. As the
power supply line and communication line for a bus
system are installed simultaneously, the amount of
installation work is vastly reduced. Where four lines
were previously used, two lines now suffice. In par-
ticular, when installing bus systems with multiple
participants, major benefits are offered in terms of
the installation time if only one line has to be fed to
the participants. In larger bus systems, the benefit
of material savings also plays a role.
S-Link interface for the PCD1.F2300
If you look at the existing market, you will find so-
lutions for network communication via 230 VAC
power lines – internet from the plug socket. This
relates to the transmission of large data volumes
with a high transfer rate. Sophisticated error rec-
ognition and correction algorithms ensure that the
information is correctly interpreted by the recipient.
In the field of‘smart metering’, which includes intelli-
gent meters for water, gas, electricity and heat, only
a small data volume with a low data rate is transmit-
ted. The focus in this area is on the robustness of the
system, which transfers measurement data securely
and reliably even if there is severe interference on
power supply lines.
In designing the PCD1.F2300, Saia-Burgess has
developed a power supply module with an inte-
grated Saia® S-Link communication interface for the
PCD1.M2xxx. As an efficient and robust solution,
this enables data transfer with simple protocols
such as the S-Bus or Modbus. The PCD1.F2300 is
inserted into the first socket of a PCD1.M2, mak-
ing it possible to connect the PCD1.M2xxx to an
18–48
VAC or 20–60 VDC power source. In addition
to the power supply for the PCD1.M2xxx, a 24 VDC
pickup is also available for supplying external
I/O stations. This can be loaded with up to 9 W.
To prevent the PCD1.M2xxx from being switched
off in the event of an overload, this output is short-
circuit-protected. In addition to the power supply, a
useful signal is modulated onto the power feed, thus
enabling communication via the feed lines between
several PCD1.M2xxx devices at up to 115.2 kb/s.
