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PROFIBUS DP
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4.1.2
Configuration data
The configuration data are sent from the master to the slaves with the ChkCfg request telegram; the ChkCfg
response telegram contains no data and therefore consists of only one byte, the short acknowledgment. The
configuration data describe the assignment of the DP modules to the cyclic IO data that is exchanged with
the Data_Exchange telegram during the cyclic data exchange between master and slave. The order of the
DP modules attached to a slave in the DP configuration tool determines the sequence of the associated IO
data in the Data_Exchange message frame.
4.1.3
Diagnosis data
The diagnostics data is requested by the master with a SlaveDiag request telegram without data, the slave
sends the diagnostics data with a SlaveDiag response telegram. The diagnostic data consists of the
standard DP diagnostics (for example, state of the slave, IdentNumber) and application-specific diagnostics
data.
4.2 Cyclic data transfer
Core piece of the DP record is the cyclic data transfer. During the DP cycles the master exercises an IO data
transfer with each slave. The master send each slave the outputs with a DataExchange request telegram
and the slave answers with the inputs in a DataExchange response telegram. All output and input data are
transmitted each with a telegram in which the DP configuration (sequence of the DP module)
defines the
assignment of the output or input data to the real process data of the slave.
