The Special Properties Of Sinaut St7Sc - Siemens SINAUT ST7 System Manual

Introduction to the SINAUT ST7 system
1.11 SINAUT ST7sc SCADA Connect software
Figure 1-27
1.11.1

The special properties of SINAUT ST7sc

Acquiring process data
The SINAUT station acquires the process data when it changes and transfers this to
SINAUT ST7sc over the WAN. Here, the received SINAUT messages are decoded and
stored in the ST7sc variable management as specified in the configuration An OPC client
can read this received data from the ST7sc variable management over the "Data Access"
OPC server interface. This reading is either synchronous or asynchronous (recommended);
in other words, the OPC server interface transfers data only when there have been changes
in the ST7sc variable management.
In the other direction, the OPC client can write data to be sent to a station (for example,
commands, setpoints, parameters) over the OPC server interface to the ST7sc variable
management. This is converted into SINAUT data messages and sent over the WAN to the
SINAUT station specified in the configuration.
Item buffering technique
One special feature of the SINAUT system is that process data is protected from loss. If, for
example, the connection between the station and the control center breaks down, the station
stores all the data changes acquired during the breakdown locally along with a time stamp.
This means that connections can break down for several hours or even several days without
loss of data. To make sure that the data stored on the stations arrives safely at the OPC
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Control center system and SINAUT ST7sc with attached SINAUT stations
System Manual, 07/2009, C79000-G8976-C178-07
Station control system