Configuring a Logger¶

A logger defines when data should be stored and where it should be saved. Loggers are configured in WideQuick Designer® and write data to a connected database, which can then be used by the History view, Reports, and other modules that rely on historical data.

Multiple loggers can share the same database connection. To create a logger, right-click Loggers in the project tree and select Add Logger.

Logger settings

Logger settings¶

Logger type¶

The logger type determines what triggers data to be stored.

Type	Description
Cyclic	Logs all variables at a fixed time interval.
Change	Logs each time a variable value changes. Changes are queued to avoid delays and flushed at the configured interval.
Trigger	Logs all variables when triggered by a script using `Loggers._LoggerName_.trigger()`.
Alarm	Logs alarm status changes. Database storage only. Supports wildcards — for example `alarmgroup.*` logs all alarms in a group.
Event	Logs system events triggered by `System.logEvent()`. Database storage only. Filterable by context using `;` separated values.
User	Logs all user system events such as logins and user modifications.

Note

When using Change or Trigger with File storage type, values are stored with 16-bit precision. Ensure the variable's min and max are correctly configured and that the difference between them does not exceed 65535.

Storage type¶

Select Database or File as the storage destination.

Tip

Database is strongly recommended. File storage is less reliable, scales poorly, and has reduced precision when used with Change or Trigger logger types.

Interval¶

Sets how frequently data is logged, configurable in seconds and milliseconds. The minimum interval is 0s 100ms and the maximum is 3600s.

Enable variable¶

An optional boolean signal that enables or disables the logger. When the signal is false the logger is paused. Useful for limiting logging to specific time periods or conditions.

Database settings¶

Database settings

Version¶

Select version 1 or 2. Version 2 is recommended as it is more storage efficient, using binary blob encoding to reduce database size.

The key differences between the versions are:

Version 1 cannot log variables of type Int64 or UInt64
Version 1 creates two tables named after the logger, while Version 2 creates multiple auto-generated tables depending on the number of variables logged
Version 2 stores all data in binary format (database blobs), while Version 1 stores data as their corresponding database types

Note

To retrieve data from a Version 2 logger, use Logger.data() rather than querying the database tables directly.

Database connection¶

Selects which database connection the logged data is stored in. Multiple loggers can share the same database connection.

Remove data older than¶

Automatically removes logged data older than the configured threshold, set in days, hours, and minutes. This is the recommended approach for managing database size over time.

Remove data when diskspace is low¶

Warning

This option is not recommended. Use Remove data older than to manage database size instead.

Variables¶

Variables

The Variables tab defines which signals are logged. Signals can be added in two ways:

Browse — opens the Data Store browser to select a specific signal
Add — adds an empty row where a signal name can be entered manually

Wildcard suffixes are supported. For example *_kWh logs all signals ending in _kWh, making it easy to capture a group of related signals without listing each one individually.

The Hysteresis column is available for numeric signals and defines the minimum change in value required before a new entry is logged. This is useful for reducing noise in logged data.