QuickOPC DA COM VB6 [order of item change events] - by: support

From: J.
Sent: Wednesday, June 15, 2016 6:20 AM
To: Z.
Subject: QuickOPC DA COM VB6

Hello [...],

we user QuickOPC DA COM in a VB6 application to connect to a softing OPCServer which connects to a Siemens S7-PLC.

Our S7 datablock (in ascending address order), every data has it's corresponding OPCvariable in the OPCserver :


The framewords are incremented simultaneously in the plc every 200-500ms.
The OPCServer polls the datablock in intervalls of 500ms.

In our application we use QuickOPC with SyncReadGroup (GroupReadTime = 1000ms).
We receive the ChangedEvents for each frameword opc variable and the data opc variables.
If one of the data opc variable is changed we log the frameword and data to a file.

Here a part of the log file entries in chronological order (values are upper/lower frameword)r:

Here my question:
Could there be a situation in QuickOPC were the frameword change events with older data were raised after the change events with newer data, not in chronological order ?

See the marked log-entry B:
The value of the lower frameword has an old value, although the previous raised event (previous log entry A) has an value which is greater (newer).

Do You have an idea, what is the problem ?

Best regards.
J.