Endress+Hauser PROFIBUS-DP, Operating Instructions Manual

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SmarTec S CLD 132 PROFIBUS-PA/-DP Operation
Hauser 29
5.3.4 Acyclic data exchange
Acyclic data exchange is used to transfer parameters during commissioning, during
maintenance or to display other measured variables that are not contained in the useful
cyclic data traffic.
Generally, a distinction is made between Class 1 and Class 2 master connections.
Depending on the implementation of the transmitter, it is possible to simultaneously
establish several Class 2 connections.
•
Two Class 2 masters are permitted with SmarTec S. This means that two Class 2
masters can access the transmitter at the same time. However, you must make certain
that they do not both attempt to
ÜÀˆÌiÊ
to the same data. Otherwise the data
consistency can no longer be guaranteed.
•
When a Class 2 master reads parameters, it sends a request telegram to the
transmitter specifying the device address, the slot/index and the expected record
length. The transmitter answers with the requested record if the record exists and is
the correct length (byte).
•
When a Class 2 master writes parameters, it transmits the address of the transmitter,
the slot and index, length information (byte) and the record. The transmitter
acknowledges this write job after completion. A Class 2 master can access the blocks
that are shown in the illustration.
The parameters, which can be operated in the Hauser operating program
Commuwin II, are displayed in the form of a matrix on Page 38.