Shared Variable Engine Buffering Enable/Disable

[decroosj]

Hello -

I am running into a problem where I am seeing a read of data that seems to be lagging the writing of the data. The reading and writing functions are utilizing the same shared variable - a control to write to it and an indictor to display it somewhere else. The indicator is lagging by one value, ie. scrolling up the value from 1,2,3,4.. will yeild in a display of 0,1,2,3, lagging by one. I am writing/reading to/from a value in a PLC using an OPC server, binding the variables to the control/indicator.

I am assuming it is the buffering which is causing this, but I can not seem to find where the buffering is enabled/disabled.

Has anyone seen this behaviour before? Also, where do you configure the Shared Variable Engine to disable buffering?

Thank you in advance for your help -

John

PS> One other note, Datasocket binding of the control/indicator does not yield any problems.

[Paul M.]

John,

Buffering is configured in the main window of the shared variable (double click on the shared variable in the project).  Also, you will see this behavior if you have the RT FIFO enabled and you're using the variable on a Real Time target. 

I would also recommend taking a look at this white paper which covers the workings of the shared variable:
http://zone.ni.com/devzone/conceptd.nsf/webmain/5b4c3cc1b2ad10ba862570f2007569ef