Siemens RWF55.5 User Manual page 76

Cyclical data traffic
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Building Technologies Division
Infrastructure & Cities Sector
Protection functions

Threshold monitoring for DP slaves

Access protection for inputs/outputs of DP slaves

Monitoring of user data traffic with adjustable monitoring timer for DP master
Device types

DP master class 2, e.g., programming/configuration devices

DP master class 1, e.g., central automation devices such as PLC, PC, etc.

DP slave, e.g., devices with binary or analog inputs/outputs, controllers, recorders,
etc.
Data traffic between the DP master and DP slaves is automatically processed by the
DP master in a fixed, constantly recurring order. The user specifies the assignment of a
DP slave to a DP master during bus system configuration. The DP slaves to be
included in or excluded from cyclical user data traffic are also defined.
The data traffic between the DP master and DP slaves is divided into parameter
setting, configuration, and data transfer phases. Before a DP slave is included in the
data transfer phase, the DP master checks (in the parameter setting and configuration
phase) whether the desired configuration that has been configured matches the actual
device configuration.
As part of this check, the device type, format information, and length information as well
as the number of inputs and outputs must match. As a result of this, the user is
provided with reliable protection against parameter setting errors. As an addition to the
user data transfer function that the DP master performs automatically, it is also possible
to send new parameter setting data to the DP slaves if requested by the user.
Figure 40: User data transfer with Profibus DP
User Manual RWF55...
12 Profibus-DP interface
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