Database

class pyhades.logger.DataLoggerEngine(*args, **kwargs)

Data logger Engine class for Tag thread-safe database logging.

set_db(self, db)

Initialize a new DB Object SQLite - Postgres - MySQL

Parameters

• db (db object): Sqlite - Postgres or MySql db object

Returns None

get_db(self)

Returns a DB object

create_tables(self, tables)

Create default PyHades database tables

['TagTrend', 'TagValue']

Parameters

• tables (list) list of database model

Returns None

drop_tables(self, tables)

Drop tables if exist in database

Parameters

• tables (list): List of database model you want yo drop

set_tag(self, tag, unit, data_type, description, min_value=None, max_value=None, tcp_source_address=None, node_namespace=None)

Define tag names you want log in database, these tags must be defined in CVTEngine

Parameters

• tag (str): Tag name defined in CVTEngine
• period (float): Sampling time to log tag on database

Returns None

write_tag(self, tag, value)

Writes value to tag into database on a thread-safe mechanism

Parameters

• tag (str): Tag name in database
• value (float): Value to write in tag

read_tag(self, tag)

Read tag value from database on a thread-safe mechanism

Parameters

• tag (str): Tag name in database

Returns

• value (float): Tag value requested