Data logger

A data logger samples the values of one or more variables at user-defined intervals or at every value change and stores them in a database.

Tip: You can disable automatic sampling by setting the Sampling mode property to None.

Database configuration

Databases are automatically configured for data loggers.

When you select a database for a data logger, a database table with the following columns is automatically created for each variable to sample:


Column	Description	Present
`[VariableToLogName]`	The value of a specific variable	Always
`[VariableToLogName]_OpCode`	The variable code of the reading operation on the controller	If `Log operation code of the variable = True`
`[VariableToLogName]_Timestamp`	The date and time (UTC) of the variable reading on the controller	If `Log timestamp of the variable = True`
`Timestamp`	The date and time of the sample reading on the controller. This timestamp refers to the time when FactoryTalk Optix Studio stops reading all sample variables.	Always
`LocalTimestamp`	The date and time of the variable reading on the controller in the machine local time zone.	If `Local time log = True`

Automatic sample modes

A data logger can automatically sample:

All monitored variables

The data logger samples all monitored variables regardless of their values.

Only the variables with significantly changed values

Change in value sampling mode applies only to the variables with significantly changed values.

The data logger samples only the variables which values vary beyond a deadband interval in comparison with the previous sampling. The deadband interval value can be an absolute or percentage value.

For example, if the deadband interval is set to 5, the data logger samples only the variables that have an absolute or percentage variation of at least ±5 in comparison with the previous sampling.