"null" values in Data Logger Database during each power ON

[vinit_patil]

Hi,
I am using Qterm A12 Panel with iX Develope 1.31.
I have to log the data using a "Log on Tag Change" event
Though i have initialized value of the TAG used for log on tag event to "0" during power on there are "null" values found during each Power ON.

I have created settable timer to change the TAG value fro log on Tag event.
timer1 = new Timer();
timer1.Tick += new EventHandler(TimeOut1);
timer1.Interval = Globals.Tags.SamplingInterval.Value*1000;
timer1.Enabled = false;
SamplingInterval tag checked fro NonVolatile memory
timer1 will only start whent START LOG button is pressed.
Once the Timer 1 satrts Tag value assigned to log on Tag event will incremented by 1 & data will get recorded accordingly.
that means @ power up condition TAG value is "0" so no data should not get recorded in data logger then why there are "null" values getting recorded?

[mark.monroe]

This is by the design. The trend viewer uses the null values to determine
if there should be a gap in the trend curves. When the TrendViewer finds
null values there will be a gap between the null values (time stamp) and
the next sample in the table.

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[vinit_patil]

It is Ok in the case of Trend Database.
But i have used the data base logger to log the values in database table.
For which TAG used is initialized to "0" value at power up.
According to documentation if TAG value change other than "0" then only database logs the data.
Why there should be any "null" values recorded when we use the DATABASE LOGGER to log the values.

[mark.monroe]

In iX 2.0 the trend viewer uses a datalogger to log data. Since the datalogger doesn't know whether it is being used in a TrendViewer or not, it logs null values for the reasons mention previously. Because the data is in a database, you can always write a SQL query and only pull out non-null rows.

[jcjelektro]

Hello Mark

Is it possible to remove the function there makes the "Null" Values?

- Emil

[mark.monroe]

No you can not get iX to stop inserting null values into the data stream. You can remove any null lines by using a data analysis or text processing program.