From OpenSCADAWiki
Communication protocol of the devices is based on ModBus but with registers size 4 bytes instead standard 2 bytes, that is they cannot be polled by the standard OpenSCADA module DAQ.ModBus. So, the template implements that protocol variant on the Logical Level and with main features of the DAQ.ModBus module, that is allows for free registers specifying. On ground the module later was created the "ModBus base (mbBase)" template as a base for further creation related to ModBus templates with standard functions and additional implementing only specific functions.