Measurement Data Acquisition for Off-Board Supported Diagnostic Functions – Arithmetic and Simulative View

This paper shows the arithmetic basics for calculation of generated bus load increase imprinted by an external diagnostic tool in in-vehicle CAN bus networks. These serve as a starting point for the mathematical and simulative consideration of a method for realization of data acquisition for off-board and model-based vehicle and system diagnostics, which was previously presented at the 5th Shanghai-Stuttgart Symposium on Automotive and Powertrain Technology in October 2021 [1]. As shown in the previous publication, standardized diagnostic services from ISO 14229 are used for this purpose to record vehicle measurements in order to implement off-board diagnostic functions. By means of the derived functions, the potential of combination of UDS services and advantages of parallel diagnostic communication of an external diagnostic tool with several vehicle ECUs can be demonstrated in arithmetic form. The desired method offers the possibility to collect data from vehicle with the efficiency of the calibration and measurement protocol XCP and with a significantly lower risk of disruption of in-vehicle communication. As a result, the method can be used for data acquisition in dynamic operation in production vehicles.