Retain level is a property of a variable that determines the variables persistence during restarts. This is important for saving user-configured values or specific application data that should survive a reboot.
Variable Values Storage
Variable values are stored in the following way:
Flash memory is used to store most variable values, so they survive power failures and server shutdowns.
SDRAM, that is a temporary memory, is used for frequently collected values to avoid wearing out the flash memory.
User Configured Retain Levels
All variable has a retain level that can be configured by the user. The retain level controls if the value of the variable is retained after a restart. The retain levels affect:
The default setting for retain level in the variable is Warm start.
Table : User Configured Retain Levels and Restart Mode
|
Restart mode
|
Retain level configured by user:
No
|
Retain level configured by user:
Warm start
|
Retain level configured by user:
Cold start
|
|
Warm start
|
Values configured by a user or application are lost.
|
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.
|
|
Cold start
|
Values configured by a user or application are lost.
|
Variable loses last value configured by a user.
Values configured by an application are lost.
|
Variable retains last value configured by a user.
Values configured by an application are retained.
|
Retain Levels for Events and Activities
A restart can be initiated in a number of ways.
Table : Retain Levels for Certain Events and Activities
|
System Events and Activities
|
Initiated from
|
System response
|
Variable retain level
|
|
Warm start command
|
WorkStation
|
Application restarts
|
Warm start
|
|
Cold start command
|
WorkStation
|
Application restarts
|
Cold start
|
|
Restart command
|
Device Administrator
|
Full device restart
|
Warm start
|
|
Power fail
|
X
|
Full device restart
|
Warm start
|
|
Restore (from a backup)
|
WorkStation
|
Application restarts
|
Warm start
|
|
Upgrade
|
WorkStation
|
Full device restart
|
Warm start
|
|
Exporting & Importing
|
WorkStation
|
Application restarts
|
Warm start
|
|
Reset button
|
One short push on Reset button on field server.
|
Full device restart
|
Warm start
|
Function Block
Function block objects have their own backup function. The backup function in Function Block overrides the retain level in EcoStruxure BMS for a warm start.
Pour plus d'informations, voir Function Block Program - Retain Versus Backup
.