The COV (Change of Value) history extension is used to collect data whenever a specific change of value occurs. If the COV option is chosen in the NV component, a history COV component is created under the history service, and a link with NV point Out slot is made. For configuration settings please refer to historical components under the history service.
WARNING! To delete or change a historical extension type, do not remove it manually from the history service. Go to the NV component, choose the None option in the history slot, and save it (extension will be deleted by the system, along with all the database settings). In order to change the type, choose the None option first, save, and after that choose the required option.
The component has the following slots:
- Status: shows the history component status;
- Enable: allows to enable or disable collecting the history logs;
- Resv Size: allows to set the history memory reserve size;
- Description: allows to enter a component’s description;
- Capacity: shows the number of available history records;
- Deadband: allows to save hysteresis,
- Input: current value;
- Last Value: shows the last saved value.