Openpcs 7 Interface; Access Options; Data Transmission - Siemens SIMATIC PCS 7 Function Manual

OpenPCS 7 interface

6.1

Access options

Access options
The following table lists the options for access to the PCS 7 OS server and the central archive
server via OPC:
Access to data
from
OS server
OS server
OS server
OS server
Central archive
server
Central archive
server
6.2

Data transmission

Type of data transfer of OPC DA, OPC HDA and OPC A&E
This section explains the various types of data transfer.
Event-driven data transfer
With event-driven data transfer, the OPC registers the required data for updating on the OPC
server. The OPC server sends the tags to the OPC client when they change.
Asynchronous data transfer
When using asynchronous data transfer, the called method is not completely processed on
the OPC server before the OPC client receives data from the OPC server. The OPC server
returns the results of the asynchronous operations using events. In this way, it is possible for
the OPC server to supply data to the OPC client automatically if the data has changed.
OpenPCS 7
Function Manual, 05/2012, A5E02780178-02
Access Data type
via OPC
DA Tags in process mode
HDA Archive tags in the measured value archive
(TagLogging)
A&E Alarms and messages
"H" A&E Alarms and messages from the message archive Read
"H" A&E Alarms and messages from the message archive Read
HDA Archive tags in the measured value archive
(TagLogging)
6
Type of access
Reading / writing
Read
Read/
acknowledge
Read
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