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S-Net
S-Bus
S-IO
Communication & Interaction
Serial protocols with standard interfaces
IP-based protocols
Dedicated communication systems
Saia PCD® systems provide communication protocols suitable for all levels of the automation pyramid to integrate a PCD into
the communication infrastructure of a building. In addition to performing regulation and control tasks, the PCD is often used
for connecting different systems from different building services. Regardless of the type of interface, it is recommended to use
only standardised communication systems for heterogeneous systems. From experience, compatibility and sustainability are
better solved using standard technologies rather than closed solutions from a single manufacturer. The following diagram il-
lustrates the essential differences between communication systems, from the field to the management level.
IP-based protocols are mainly used for connecting controllers to management systems. IP
protocols are also used to exchange data between automation devices and with local control
devices. For example, BACnet is very good for communicating between automation devices
and the management system. Web and IT services such as DHCP, DNS, SNTP, SNMP and SMTP
(emails) are reliable tools in the integration of automation devices into the IT infrastructure.
Web-based visualisations with suitable web servers and a CGI-bin interface in the automation
device also provide a sustainable basis for operation and service over the entire service life
of a system.
Field components mainly use serial protocols equipped with standardised interfaces such as
RS-232, RS-485 or RS-422. Despite the low baud rate, these interfaces have the advantage over
Ethernet as they are easy to install. Cable and infrastructure components such as repeaters are
cheaper than a complete IT infrastructure. Field bus systems are also easier to service and maintain.
It is practical to use a dedicated hardware interface for certain field devices. These systems are
optimised for particular tasks. DALI is suitable for controlling lighting for example, and M-Bus is
designed for connecting meters. However, these systems should not be used for communica-
tion between automation stations.
Numerous protocols can be used simultaneously across all levels.
Management level
Automation level
Field level
2.1
The basic features of Saia PCD® communication systems
