The NVBooleanWritable is the component that stores the output value in the non-volatile EEPROM memory of the device. After rebooting the device or in case of the power failure, the component value is restored from this memory. The iSMA-B-AAC20 controllers have 1536 Boolean memory cells. The occupied space meter for EEPROM is embedded in the plat component. The NVBooleanWritable component occupies two Boolean memory cells (value of the component and the position of the Auto/Hand switch).
The NVBooleanWritable component is also used to integrate Boolean variables from various sources. This is done using the 'reverse following the link' function. The Out slot is connected to the In slots of various protocols, for example, LCD or Modbus variable. When changing a value in one of the components, the device will perform the Set action on the NV component to synchronize the values in all the connected components.
The NVBooleanWritable component has the following slots:
- Status: shows the current status of the component (Auto/Hand);
- Alarm: alarm extension;
- History: history extension;
- Totalize: totalize extension;
- Out: the output slot,
- In: the input slot,
- User: the user value slot (introduced by the Set action);
- Default: the default value slot (set by global command from the plat component);
- Default Trigger: copies trigger from the Default slot to the Out slot.
The NVBooleanWritable component has the following actions:
- Set: allows to manually set the User slot and the In slot if there is no link to the In slot;
- Set In Hand: this option sets the value on Out slot and blocks changing from any other slots;
- Set In Auto: this option switches off the Hand mode and sets Out slot according to the In slot’s value.
The NVBooleanWritable component allows adding extensions such as:
- Alarm Change Of State: generates alarms when the component is in a particular state;
- History: records the value at a specific point in time, over a defined period of time at a change by a certain value, or in both of these cases;
- Totalize: counts the time over which the value of a point is in a particular state.