Real Time and Historical Trends

Trends:-

A trend is a graphic representation of the values that a tag takes during runtime. In order to
display trends, configure a trend view in a screen of your project.
To configure the trend view, specify a trend type for the values to be displayed.
● Log: For displaying the logged values of a tag
● Cyclical real time: For time-triggered display of values
● Bit-triggered real time: For event-triggered display of values
● Bit-triggered buffer: For event-triggered display with buffered data acquisition

Displaying logged values:-

In Runtime, the trend view displays the values of a tag from a data log. The trend shows the
logged values in a particular window in time. The operator can move the time window in
Runtime to view the desired information from the log.

Pulse-triggered trends:-

The values to be displayed are determined individually with a definable time pattern. Cyclicallytriggered
trends are suitable for representing continuous curves, such as the changes in the
operating temperature of a motor.

Bit-triggered trends:-

The values to be displayed are event-driven by setting a defined bit in "Trend transfer" tags.
The bit is reset after reading has been completed. Bit-triggered trends are useful for displaying
fast-changing values, such as the injection pressure for producing plastic parts.

Bit-triggered trends with buffered data acquisition:-

When you set buffered data acquisition, the values to be displayed are buffered in the PLC
and read in bit-triggered as a block. These trends are suitable for displaying rapid changes
when the course of the trend as a whole is interesting and not so much the individual values.
You configure a switch buffer in the PLC so it can continue to write the new values while the
trend buffer is being read. The switch buffer ensures that the PLC does not overwrite values
while the operator devices reads the values for the trend.

The switch between the trend buffer and the switch buffer functions as follows:
Whenever the bit assigned to the trend is set in the "Trend transfer 1" tag, all the values are
read simultaneously from the trend buffer and are displayed as a trend on the HMI device. The
bit in "Trend Transfer 1" is reset after reading has been completed.

Configuring trend displays for values from the PLC

To configure a trend view, follow these steps:
1. Add the "Trend view" object from the toolbox in the "Controls" group to the screen.
2. Select "Properties . Properties > Trend" in the Inspector window and double-click "Add" in
the "Name" field. A new trend is created.
3. If required, enter a unique name for the trend in the "Name" field.
4. In the "Style" column, use the selection button to open the "Style" dialog and select the
style of the line.
5. Select the number of trend values in the "Trend values" column.
6. In the "Trend type" column, select the required trend type. The following entries are
available:
7. In the "Settings source" column, use the selection button to open the "Data source" dialog
and select the tags to supply the trend with values.
8. You can make other settings in the dialogs of the Inspector window. For example, you can
select the "Display table" option in the "Table" category to display a value table beneath
the trend view.

Trend Configuration in RT Advanced Using TIA Portal.



Trend Configuration