Knowledge Base

All variable properties are saved in Varexp.dat file (c directory of the project). In a multi-station configuration, PcVue is capable of distributing the variables value and also some variables properties.

There are 5 dynamic* properties that can be distributed**:

1. Alarm priority (Alarm variable)
2. Alarm direction (positive or negative activation of Alarm variable, always distributed)
3. Thresholds (Register, always distributed)
4. Extended binary and text attribute (Bit, Alarm, Register, Text)
5. Deadband value and type of deadband (Register, always distributed since PcVue 15)Deadband value and type of deadband (Register, always distributed since PcVue 15)

*Dynamic: can be changed at runtime but remains local to the station.

**Distributed: can be changed at runtime and distributed to other stations.

How do the backup, the runtime rewriting  and the modification of distributed properties work?

The behavior of these five properties is not identical, thus we must detail its functioning by property.

• Alarm priority
  The alarm priority is saved in the Varexp.dat, it is the configuration value.
  If the alarm has the saved option then the runtime value of priority is saved in the AlarmSaved.dat file.
  Using Scada Basic ALARM instruction (variable by variable), you can change (SETALARMLEVEL mode) or restore (RESTOREALARMLEVEL mode) its value.
  You can also change it, for a whole set of variables, with the SVBRANCH instruction (modification by branch).
• Alarm direction
  The alarm direction is saved in the Varexp.dat, it is the configuration value.
  If modified dynamically, this property is never saved, even if the alarm is saved (AlarmSaved.dat).
  The alarm direction can be modified with the Scada Basic ALARM instruction and the ALARMON mode (variable by variable).
• Thresholds
  Thresholds are saved in the Varexp.dat, it is the configuration value.
  If you dynamically change a threshold, it will only be saved in the varexp.dat, either by the Scada Basic VARIABLE instruction SAVE mode, or by registering variables (save button in the variable selector before PcVue 10.0 or Application Explorer with the diskette icon on PcVue 10.0).
  The modification of thresholds is possible through the Scada Basic VARIABLE instruction using THRESHOLD_SETVALUE mode (variable by variable).
  Note:  SAVEFLAG, optional argument of this instruction, can make the threshold change, temporary (value 0) or permanent and saved when the software is shut down (Value 1)
• Extended text and binary attributes
  Extended attributes are saved in the Varexp.dat, it is both the configuration and the runtime value.
  If you dynamically change them (saved option is checked) then runtime value of the extended attributes are saved in the VariableSaved.dat file. If you save the varexp.dat by the Scada Basic VARIABLE instruction SAVE mode , or by registering variables  (variable selector or Application Explorer), the runtime value will also be saved.
  The modification of extended attributes is possible through the Scada Basic VARIABLE instruction using the SETBATT and SETTATT modes (variable by variable).
• Deadband and deadband type
  These two properties of a register are saved in the Varexp.dat, they are the configuration value.
  If modified dynamically, these properties are never saved, even if the register is saved (VariableSaved.dat).
  The dead band value and type can be modified with the Scada Basic VARIABLE instruction and the SET_DEADBAND mode (variable by variable).

How to configure these properties outside PcVue in a single station architecture: (Case N°1)

Depending on the presence or not of the option saved for the variable, variable properties will be taken into account from different files:

• If there is no saved option, PcVue takes into account variable properties from Varexp.dat.
• If the saved option is activated for variable extended attributes then the VariableSaved.dat is taken into account for extended attributes and the Varexp.dat for other properties.
• If the saved option is activated for alarms then the file AlarmSaved.dat is taken into account for alarm priority and Varexp.dat for other properties.

Note: Thresholds, deadband, deadband type and alarm direction are necessarily taken into account from the Varexp.dat file.

How to configure these properties outside PcVue in a multi-station architecture without redundancy: (Case N°2)

• Undistributed properties
  Identical case N°1
• Distributed properties
  Client stations retrieve the variables properties values coming from the server station. Consequence: all modifications made locally in the configuration file (Varexp.dat) or in the Variablesaved (or Alarmsaved) file of client station are not taken into account.
  Server station, same as case n°1

How to configure these properties outside PcVue in a multi-station architecture with a single active server redundancy: (Case N°3)

• Undistributed properties:
  • Alarm priority
    If the alarm priority is not distributed (note that the distributed option is set by default) then we are in case 1. In other words if the saved option is activated, the alarm priority is retrieved from the AlarmSaved.dat file otherwise from the Varexp.dat file.
  • Alarm direction
    Always distributed.
  • Thresholds
    Always distributed
  • Extended text and binary attributes
    If the extended attribute is undistributed (note that the dynamic option is set by default) then we are in case N°1. In other words if the saved option is activated, the extended attribute is retrieved from the VariableSaved.dat file otherwise from the Varexp.dat file.

• Distributed properties
  In a multi-station architecture, the variable properties of the active server are distributed to all stations.
  Consequently, all distributed properties modifications made locally in the Varexp.dat file or the VariableSaved.dat or the AlarmSaved.dat files will not be considered, as long as an active server is running.
  Therefore, in order for PcVue to use the modifications coming from those modified files:
  • All the servers of the realtime association must be stopped.
  • Server with modified files must then be restarted

How to take into account modifications without stopping all servers

Following rules must be applied to the properties below.

• Alarm priority
  • In order to change alarm priority:
    1. Standby server station must be stopped
    2. The alarm priority must be changed, using an editor, in the Varexp.dat file of the Standby server (or AlarmSaved.dat if the alarm is saved)
    3. When Standby server station is restarted, alarm will be overwritten by the one coming from the active server
  • In order to recover the priority coming from the configuration file
    1. Standby server must then be switched to active
    2. The alarm priority must be restored by using the Scada Basic « ALARM » instruction RESTOREALARMLEVEL mode or « SVBRANCH » instruction RESTOREALARMLEVEL mode which both allows you to recover the configuration value. 

Another solution –  To modify this property, you can also realize a dynamic import on the active server (XML import or Scada Basic VARIABLE instruction IMPORTFILE mode).

• Alarm direction
  To modify this property, you can also realize a dynamic import on the active server (XML import or Scada Basic VARIABLE instruction IMPORTFILE mode) or use the ALARM instruction ALARMON mode.
• Thresholds
  To modify this property, you can also realize a dynamic import on the active server (XML import or Scada Basic VARIABLE instruction IMPORTFILE mode) or use the VARIABLE instruction THRESHOLD_SETVALUE mode.
• Extended text and binary attributes
  To modify attributes, you can also realize a dynamic import on the active server (XML import or Scada Basic VARIABLE instruction IMPORT mode) or use the Scada Basic VARIABLE instruction SETBATT and SETTATT mode.
• Deadband and deadband typt
  To modify these properties, you can also realize a dynamic import on the active server (XML import or Scada Basic VARIABLE instruction IMPORTFILE mode) or use the VARIABLE instruction SET_DEADBAND mode.