About

Activate the history in order to store a certain amount of past values for a variable.

This is the requirement for using Elements such as Trend (Element).

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Every

What is the frequency at which HELIO should record a value?

For

Specify the length of time for which HELIO will record the history of this variable. See Disk Space Usage and Limitations to get a feeling how much this affects the disk space of your target device.

When Are These Settings Applied?

Changing those settings does not immediately start recording history. It is also important to know which one of the Data Connection Modes (Preview Panel) you are currently using.

When will changes take effect? Which data will get used?
Placeholder Mode Immediately Simulated values which are based on the minimum and maximum values.
PLC Mode When project is saved Actual historical data stored by HELIO. Depending on your chosen settings, it may take some time before any data is visible.

Disk Space Usage

Storing historical data will take up extra space on your device. Make sure to plan for this and reserve space on the hard drive of your target device. It is not always sensible to use a high resolution with more than 1000 samples if you do not need to display a correspondingly smaller section graphically.

Every For Required Disk Space
1 s 15 min 0.26 MiB (900 Samples)
1 s 1 h 1.0 MiB (3600 Samples)
2 s 4 h 2.1 MiB (7200 Samples)
10 s 24 h 2.5 MiB (8640 Samples)
60 s 1 week 2.9 MiB (10080 Samples)

Limitations