Concept
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 field 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.
|
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.
Warm start retained variables are retained during a cold start of the controller, if the user has configured or changed the initial property value. Conversely, if the warm start retained variable is changed by a system application, such as a program, the value are not retained during controller cold starts.
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.
|
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 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 .
Configuring the Retain Level
Configure Dialog Box – Configuration Tab
Edit Block Dialog Box
Backup and Restore Overview
Mass Editing the Retain Level of Properties