Operation manual Profibus PBD 100
23.07.2007
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3
General information about PROFIBUS-DP
For the exchange of information among automation systems and between automation systems and the connected decentral field devices,
serial field-buses are mainly used today as the communication system. Thousands of applications have proved impressively that cost
savings of up to 40 % in wiring, commissioning and maintenance are achieved by using field bus technology. Just two wires are needed to
transmit all relevant information for the field devices, such as input and output signals, parameters and diagnostics data. While in the past
the fieldbuses used were often manufacturer specific and incompatible with other bus systems, the systems employed today are almost
exclusively open and standardized. This means that the user is independent of individual suppliers and can choose the best product for the
most competitive price. PROFIBUS-DP is the leading open fieldbus system in Europe, which is also used successfully throughout the world.
The application range includes automation in the areas of manufacturing, processing and building. PROFIBUS-DP is an international, open
fieldbus standard, which has been standardized in the fieldbus standard EN 50 170. This standardization ensures that the investments of
manufacturers and users are protected to the best possible degree and the independence of the manufacturer is guaranteed. These
operation instructions cannot provide a general introduction to PROFIBUS-DP.
3.1
Basic characteristics
PROFIBUS-DP determines the technical and functional features of a serial fieldbus system with which distributed digital automation devices
can be interconnected. PROFIBUS-DP distinguishes between master and slave devices. PROFIBUS-DP is designed for fast data
transmission in the field level. Here central control devices, such as a PLC or PC, communicate via a fast serial connection with peripheral
field stations such as input/output devices, valves and actuators. The interchange of data among the field devices takes place cyclically. The
necessary communication functions are established by the PROFIBUS-DP basic functions according to EN 50 170.
Master devices
control the data traffic on the bus. A master is allowed to send messages without an external request. Masters are also
called ‘active stations’ in the PROFIBUS protocol.
Slave devices
such as PROFIBUS PBD 100 actuators are peripheral devices. Typical slave devices are input/output devices, valves,
actuators and measuring sensors. They do not have bus access, i.e. they may only acknowledge received messages or, at the request of a
master, transmit messages to that master. Slaves are also called ‘passive stations’.
3.2
Basic function of PROFIBUS-DP
The master reads the input information from the slaves cyclically and writes the output information cyclically to the slaves. In addition to this
cyclic data transfer of the process representation, PROFIBUS-DP also provides powerful functions for diagnostics and commissioning
purposes. The data traffic is monitored through the monitoring functions on the master and slave side.
3.3
Transfer mode
RS-485 twisted pair cable or fibre optical cable.
PBD 100 support baudrates up to 1.5 MBits/s
3.4
Bus access
Token-passing between the masters and polling between master and slave.
Mono-master or multi-master systems are possible.
Master and slave stations: max. 126 stations connected to one bus.
3.5
Communication
Peer-to-peer (net data transfer) or Multicast (control commands to all slaves).
Cyclic master-slave net data transfer or acyclic master-master data transfer.
3.6
Functionality
Cyclic net data transfer between DP slave and DP slaves.
Dynamic activation or de-activation of individual DP slaves.
Checking of the configuration of the DP slaves.
Synchronisation of inputs and/or outputs.
3.7
Protection functions
All messages are transmitted with Hamming Distance HD=4.
Watch-dog timer at DP slaves.
Access protection for the inputs/outputs of the DP slaves.
