Omron CX-Supervisor, User Manual

Page: 168 / 334

Data Log Editor SECTION 11 Data Logging
167
keep process data for 2 years, you could keep 24 files of 1 month period. The
file names are generated automatically based on the Data Set name, plus a
suffix which is incremented by one as each new file is generated.
If the Keep all Files option is checked the data files management is disabled
and no files will be deleted.
The Start Logging on Application Startup checkbox controls the logging of the
Data Set. When selected, all the Items in the Data Set start logging when the
system is started, and stop logging when the system is stopped. If this option
is not selected, then logging must be controlled by the Start/Stop logging script
functions as required by the developer.
11-2-3 Editing Item Properties
The Add/Modify Item properties dialog box is shown when adding a new
Item , or editing an existing one.
11-2-3-1 Item Properties
These options enable an items name and associated expression to be
entered. Its data type can be selected and if required a deadband value can be
applied to the measured value.
The Item Name field allows the Item to be given a meaningful name. The entry
should be kept short but also be logical for clarification. A maximum of 26
characters is allowed.
The Expression field defines the point name or expression that will be logged.
The Browse button allows easy point selection. For details on how
expressions or points are formulated Refer to chapter 3, Points.
The Data Type field determines the type of data to be logged. Select either
Boolean, Integer or Real. For points, this is automatically picked up from the
points database. For expressions, the required type must be selected.
The Deadband field enables a percentage limit or 'Deadband' to be applied to
the logging expression. This allows the value of the expression to change
within the percentage limit without being logged. This is particularly useful
when logging analogue values which are subject to noise. Each sample is
checked (when the value changes for 'On Change' sampling, or every log
period for 'On Interval') against the last logged value. While the value varies