The iSMA-B-AAC20 controllers have an embedded historical extension for writing trends in the microSD card memory. By default, the device is not equipped with an SD card, historical service SD card should be installed when necessary. The historical extension can be added only in the NVBooleanWirtable, NVIntegerWritable, and NVNumericWritable components. To add the extension, choose one of three available types in the NV History slot components. Every historical type has predefined 2500 recordable samples. After reaching the limit, the oldest recordings are overwritten. While creating a historical record, the device opens a database file on the SD card. Any such file can serve up to 200 extensions. Once the limit is reached, the new database file is opened.
The history service is a component, which is responsible for writing historical values in the microSD memory. The history service is available in the iSMA_controlApi kit palette and the component must be placed under the service folder.
After any historical extension is added on the NV component, a historical database will be created under the history service component in order to store NV points of historical components.