Image Number 4 for United States Patent #5696776.
A data transmission method in a real-time data processing system, comprising a control unit and at least one function unit linked to this control unit through a data line, is described that permits noise-free and noise-insensitive transmission of data. In accordance with the invention, the data is stored in a buffer memory made up of a shift register and an intermediate storage, before being loaded into a main memory of the function unit. Transfer to the intermediate storage takes place only if certain conditions are satisfied that identify transmission faults. Before the data is stored in the main memory, the data is read-back into the control unit memory for the purposes of checking and there it is compared with the original data. If there is no correspondence, data transmission is performed again. The method in accordance with the invention can be applied advantageously in local networks, and in particular for motor vehicles, where a central control unit is applied for controlling operational sequences through various function units such as triggering circuits for passenger restraint systems or control circuits concerning motor management.