Explanation Of Terms "Profibus" And "Profibus-Dp - Siemens 3VF Series Communications Manual

Communication System Manual

1.3 Explanation of terms "PROFIBUS" and "PROFIBUS-DP"

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PROFIBUS (PROcess FIeld BUS) is a standard (EN 50170), supplier-independent field bus system. Over
250 suppliers are already offering more than a total of 770 PROFIBUS products in their product ranges.
There are in excess of 500,000 PROFIBUS nodes installed worldwide, and PROFIBUS users are supported
worldwide by user organizations in 12 countries.
PROFIBUS consists of a 2-core cable over which signals (bits) are transferred between PLCs and field
devices in a standardized format (protocol). Up to 125 field devices can be connected to a single
PROFIBUS network. Repeaters can be used to connect bus segments making it possible to span distances
greater than 9 km using copper cables and distances up to 100 km using fiber optic cables. The length of
the individual bus segments depends on the baud rate and whether or not there are slaves present (see
Table 1). This means that different numbers of repeaters will be used depending on the type of network.
Data rate (Kbit/s)
9.6
19.2
93.75
187.5
500
1500
12000
Table 1: Ranges of PROFIBUS network segments (2-core cable)
In addition to standard linear bus networks, it is also possible to utilize fiber optic technology together with
optical link modules (OLM ) to form redundant ring structures.
There are at present two forms of PROFIBUS: PROFIBUS-DP (Decentralized Peripherals) and
PROFIBUS-FMS (Field Message Specification).
PROFIBUS-FMS allows for supplier-independent communication between PLCs. Communication via the
FMS user interface puts functionality rather than reaction time into the foreground. Special user services
are therefore available for the logically structured data exchange of even very large amounts of data.
Very fast reaction times for a medium data volume are required for communication with field devices (e.g.
3WN6 circuit-breakers, SIMOCODE-DP). This can be achieved by PROFIBUS-DP. The typical
configuration of a PROFIBUS-DP network is as a mono-master system, i.e. the slaves are addressed by a
single master.
The openness of PROFIBUS offers many connection possibilities: a special interface (DP/AS-i link), for
example, allows the connection of Actuator-Sensor Interface (AS-i) network systems to PROFIBUS-DP
networks. All major PLC suppliers offer PROFIBUS-DP masters.
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Siemens originally referred to PROFIBUS as SINEC L2.
Version 1.0 (05/98)
Segment length (m)
with slaves
1200
1200
1200
1000
400
200
100
© Copyright Siemens AG 1998. All rights reserved.
3VF, 3WN, 3WS Circuit-Breakers
Segment length (m)
without slaves
3300
2800
2000
1600
1200
400
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