Dear AlecTek,

Here is more information about Acquisition cycle:

From manual: http://support.automation.siemens.com/WW/view/en/18796010

Acquisition cycle

The acquisition cycle determines when the HMI device will read the process value of an

external tag. Normally, the value is updated at regular intervals as long as the tag is shown

in the process screen or is logged. The interval for regular updates is set with the acquisition

cycle. You can either choose a default acquisition cycle, or define a user-specific cycle.

An external tag can also be updated independent of the display in the process screen, for

example, by triggering a value change for the tag functions. Please note that frequent read

operations increase communication load.

Hope this will help.

Best regards,

Wizard