26
MOVIDRIVE
®
PROFIBUS DFP11A
3
The PROFIBUS-DP
Interface
3.7
Parameter adjustment via PROFIBUS-DP
In the case of PROFIBUS-DP, access to the drive parameters is via the MOVILINK parameter chan-
nel which, in addition to the standard READ and WRITE services, offers a variety of other parame-
ter services.
3.7.1 Structure of the Parameter Channel
The parameterizing of field units using fieldbus systems, which do not provide an application layer,
requires the emulation of the most important functions and services, such as READ and WRITE for
the reading and writing of parameters. In the case of PROFIBUS-DP, this requires a Parameter
Process Data Object (PPO) to be defined. This PPO is transferred cyclically and in addition to the
process data channel contains a parameter channel through which acyclic parameter values can be
transferred (Fig. 23).
Fig. 24 shows the structure of the parameter channel. It generally consists of a management byte,
an index word, a reserved byte and four data bytes.
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Fig. 23: Parameter process data object for PROFIBUS-DP
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Fig. 24: Structure of the parameter channel
E
Q
Parameter channel
Parameter channel
Process data channel
Process data channel
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Management
Reserved
Index high
Index low
Data MSB
Data
Data
Data LSB
Management Reserved
Parameter index
4-byte data