How to
Creating an Interval Trend Log
You create an interval trend log to record a value of a variable at specified and regularly occurring increments of time.
The interval trend log collects data at a specific time interval. Each logged value is stored as a record in the trend log. Use this trend log when the logging interval is less than 1 hour.
You create interval trend logs using WorkStation or WebStation. In WorkStation, you configure the properties of the interval trend log to meet the specific needs of your site.
For example, in the figure below, the interval trend log records a variable every minute. The records are printed in a trend chart. The interval trend log does not record the values between the intervals.
The interval of the interval trend log is aligned with the activation time of the trend. For example, if the activation time is 09:01:00 and the interval is 15 minutes, the trend will log at 09:16:00, 09:31:00, 09:46:00, and so on.
By default, the interval log uses UTC to determine when to take the next log sample. When the interval is longer than 1 hour and you want to continue to log that interval after a Daylight Savings Time change, use Server Local Time. For example, the log interval is every 24th hour at midnight and you want to continue to log at midnight even after a DST change, so you use Server Local Time. During the DST change in the Spring, the log sample will register after 23 hours. After the DST change in the Autumn, the log sample will register after 25 hours.
An interval trend log with delta can reduce the storage of similar records, and may not fill up the storage capacity as quickly as an interval trend log with no delta.
An interval trend log with delta checks the monitored value at each interval and records the new value if it differs from the previously recorded value by more than the delta. Delta is the difference between the current variable value and the last log value. To log a variable according to the time interval, use a delta of zero.
For example, in the figure below, the interval trend log records a variable every minute but only if the variable exceeds or falls below the delta of 3. The records are printed in a trend chart. Notice that the interval trend log with delta does not record the values between the intervals, or on intervals where the variable is within the delta.
To log a variable only according to the time interval, set Delta to zero.
If an interval trend log has a delta and a calculation method that uses periods, make sure the period contains the required amount of records to generate a correct calculation. If the value does not differ from the previously logged value by more than the delta within the period, then none or too few values are recorded for the calculation.
Adapt the period so it contains the required amount of records to generate a correct calculation.
If a calculation method is connected to an interval trend log with delta, make sure that the period and delta are adapted for the calculation.
An interval trend log can be created with initial meter settings. The interval trend log supports the meter change command and meter consumption calculation. You can view the last meter change information on the interval trend log object. For more information, see Meter Function .
In WorkStation, in the System Tree pane, select the folder or EcoStruxure BMS server where you want to create the trend log.
On the File menu, point to New and then click Trend .
In the Create Object wizard, in the object type list, select Interval Trend Log .
In the Name box, type a name for the trend log.
In the Description box, type a description for the trend log.
Click Next .
In the Configure Interval Trend Log page, in the Logged variable box, enter the variable that you want to log.
Click the Set unit button
.action_zoom_plus_stroke 
In the Unit Selection dialog box, select a unit for the trend log values.
In the Prefix box, select the prefix of the unit.
Click Select .
In the Delta box, enter the minimum value change that triggers a new record.
In the Activation variable box, enter a variable to start recording values when the acitvation variable is true
In the Activation time box, enter the exact time for the recording to begin.
In the Interval time zone box, select Server Local Time to avoid problems with DST for logging intervals more frequent than 1 hour.
In the Interval box, type the log frequency.
In the Log size box, type the log size to be stored before old values are overwritten.
In the Available trend storage box, check that the available number of records is not exceeded.
In the Clear when enabled box, select True to clear the trend log every time the trend log is enabled.
Click Next .
In the Initial Meter Settings page, in the Set initial meter box, select True to enable the meter function.
In the Start time box, enter the time when the meter was installed.
In the Start value box, enter the value of the new meter when it was installed.
In the Min value box, enter the first value of the new meter after roll-over.
In the Max value box, enter the last value of the new meter before roll-over.
Click Next .
In the Connect Objects to the Trend Log page, in the Extended Trend Log box, click the Browse button to create an extended trend log and connect it to the trend log.
In the Trend Log List box, click the Browse button to create a trend log list and connect it to the trend log.
In the Trend Chart box, click the Browse button to either create a new trend chart or connect the interval trend log to an existing trend chart.
Click Create .
Interval Trend Logs
Trend Units
Trend Log Activation
Log Record Storage
Meter Function
Create Object Dialog – Naming the Object Page
Create Interval Trend Log Wizard – Configure Interval Trend Log Page
Create Trend Log Wizard – Initial Meter Settings Page
Create Trend Log Wizard – Connect Objects to the Trend Log Page
Creating an Extended Trend Log
Creating a Trend Log List
Creating a Trend Chart that Monitors a Trend Log Series