* add Modbus scanning mode * fix modbus polling for DCU 1000 * add modbus register for DCU 1000 * calculate meta values from modbus regs * update changelog * reduce code duplication * refactor modbus_scan * add additional unit tests
* add Modbus scanning mode * fix modbus polling for DCU 1000 * add modbus register for DCU 1000 * calculate meta values from modbus regs * update changelog * reduce code duplication * refactor modbus_scan * add additional unit tests