start / stop logging by button

you can make a trend view from the logged file.

Please check the linkHow to archive Tags & Alarms. You will get to know what are the different methods to create a Data Tag.

I'll try to give a small explanation regarding how to create trend view from Logged CSV file.

1. Set up a Data Log that that logs your inputs. This you can set in the Historical data\Data logs. Go for the storage location as "File-CSV" form.
If you are logging data's per minute, then in an hour 60 data's, and in a day 1440 data's. Hence set your "number of data records per log" as 1440.
Suppose if you are setting two tags in the same data log, the number of data records will be 2*1440 = 2880.

2. In communication\tags, select you required input tag. There will be an option for Data log and Logging cycle in the the "Tag" folder. select the Data log as the one you defined above and for cycle time, you can select as as you wish, 1sec, 2 sec, 5 sec, 10 min, etc.
(you can define your own cycle time in communication\cycle).

3. Now in the trends, define for the properties\x-axis value. In a day total 86400 sec are there. Hence define that value in x-axis.

4. Properties\Trend => select the trend type as "Log", and in source setting, select the log and the Tag entry from the drop down.
You can give a "Name".


Please note that if you had selected your Tag say "pressure" in the communication\tag folder for data logging, the logged file will be having a tag name as "pressure_0". Don't worry about this one.

and also while selecting from Trend Page, Properties\Trend. select the tag "pressure" only.
Only the logged data file will be having "_0" followed by the name.

hope this clears you.

rgds,
RBM