NORD Drivesystems BU0020 - Manual (Page 49)

5 PROFIBUS technology and protocol
BU 0020 GB-2612 49
A DP master Class 1 sends its status
state to all assigned and connected
slaves in a cyclic time interval which can
be configured. If the operating parameter
"Auto Clear" is set to "TRUE", the DPM1
master switches the outputs of all
associated slaves to the safe condition,
i.e. to "0" in case of failure of a slave.
DP
-
Mas
te
r
  Auftragstelegramm  

straigh
t an
s
w
e
r

DP
-
Sl
ave
end-info original data head-info
  Antworttelegramm  
head-info receipt data end-info
Fig. 7: Diagram of telegram sequence
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5.2.1 PROFIBUS DP performance level DP-V0
The basic DP function DP-V0 describes and stands for the basic functionality of the DP
communication protocol, i.e.:
• Cyclic exchange of process data / transfer of reference data
• Diagnosis specific to the station, module and channel
The PROFIBUS master cyclically reads the input information from the slaves and cyclically writes the
output information to the slaves. It must be noted that the bus cycle time is shorter than the program
cycle time of the central automation device. Components from all three device classes, DPM1, DPM2
and slaves may be used.
The PPO types 1 to 4 are available as possible telegrams. For a parameter query (reading access)
about 30 ms should be allocated, and for a parameter change (writing access), about 50ms. This is
regardless of whether one, or up to four frequency inverters communicate with the PROFIBUS master
via a PROFIBUS technology unit. Data traffic between the DPM1 and the slaves is structured into the
parameterisation, configuration and data transfer phases.
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5.2.2 PROFIBUS DP performance level DP-V1
The basic DP function DP-V1 includes extensions for process automation and a series of event-
related functions, in particular acyclic data traffic:
• Acyclic exchange of process data for parameterisation, operation, observation and alarm
processing of intelligent field devices in parallel with the cyclic reference data traffic.
• Diagnostic functions, status alarm, update alarm and alarm processing specific to the
manufacturer.
• Exchange of data during the DP slave initialisation phase
• DP Master Class 2 communication
• DP Master-Master communication
As the NORD components /PROFIBUS technology units described in this manual do not support DP-
V1 functions, their functionality is not described in further detail in this section.
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5.2.3 PROFIBUS DP performance level DP-V2
The basic DP function DP-V2 includes further extensions for the requirements of drive technology, in
particular transfer of data between slaves.
• Isochronous slave operation and cross transfer between slaves (Data Exchange Broadcast)
• Drive bus for the control of rapid sequences of movements of drive axes.