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Concept

Concept

Products: AS-B, Enterprise Central, Enterprise Server, AS-P, Project Configuration Tool

Functionalities: Basic Functionality

Product version: 3.3, 2022

7/8/2021

Retain Level

In the EcoStruxure BMS servers, variable values are primarily stored in flash memory in order to have their values survive power fail and server shutdown. However, values that are often collected are only stored in the SDRAM memory. This is done to protect the flash memory in the automation server.

Variables have a retain level that controls if the value of the variable is retained after a restart of the server. There are three retain levels. The following table lists the retain levels and whether a variable is retained after cold start, warm start, or power failure.

Table: Retain Levels

Retain level	Cold start	Warm start	Power failure
No
Warm start		x	x
Cold start	x	x	x

In addition, the retain level also defines if and when a variable value is saved in the configuration database. A new value of a variable can either be configured by a user or by an application, for example Function Block or Script.

User written variable values with warm start retained and cold start retained levels are stored in the database. These variable values are part of a backup and restore of the database.

Application written variable values with cold start retained levels are stored in the database during certain activities, such as backup and export.

Table: Retain Levels for Certain Events and Activities

System Events and Activities	Retain level: No	Retain level: Cold start	Retain level: Warm start
Cold start command	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are lost.
Warm start command	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are retained.
Exporting & Importing	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are lost.
Viewing Variable in EcoStruxure Building Operation user interface	Shows the last value configured by a user or application.	Shows the last value configured by a user or application.	Shows the last value configured by a user or application.
Backup & Restore	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are lost.
Power loss and restore	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are retained.
Upgrade	Default value ^a	Variable retains last value configured by a user. Values configured by an application are retained.	Variable retains last value configured by a user. Values configured by an application are lost.

Default value is the value the variable gets when it is created.

Function Block

Function block objects have their own backup function. The backup function in Function Block overrides the retain level in EcoStruxure BMS. For more information, see Edit Block Dialog Box .