General Information Regarding Profibus; Transmission Method; Topology - Siemens PROFIBUS PA SIPART PS2 Manual

1.2

General information regarding PROFIBUS

1.2.1 Transmission method

1.2.2 Topology

SIPART PS2 PA Manual
A5E00127926-03
The PROFIBUS-PA(PA = Process Automation) is a variant of the PRO-
FIBUS DP (DP = Decentral Peripheral) which is widely used in
manufacturing engineering.
The PROFIBUS (Process Field Bus) is an open communication sys-
tem for automation engineering and thousands are used all over the
world. It is specified in the European standard EN 50170.
The PROFIBUS PA has a special transmission method and therefore
satisfies the requirements of process automation and manufacturing
engineering. This transmission method is defined in the international
standard IEC61158--2. The low transmission speed reduces the power
loss compared to the PROFIBUS-DP and therefore enables an intrinsi-
cally safe technique for use in hazardous areas.
The bus topology can, to a large extent, be freely selected so that line,
star and tree structures are possible, as well as mixtures of these. All
kinds of field devices such as transformers, actuators, analyzers, etc.
can be connected to the PROFIBUS PA
The main advantage is in:
the saving of installation costs
S
the possibility of more extensive diagnostics with an increase in the
S
availability of system parts
the possibility of automatic tracing of system documentation
S
the possibility of system optimization in operation
S
In an automation system, several PROFIBUS PA channels are usually
connected to the fast PROFIBUS-DP with coupling units. The process
control system is also linked to this.
Both bus systems use a uniform protocol layer. This makes the PROFI-
BUS PA a communication-compatible extension of the PROFIBUS DP
into the field.
Introduction
17