Data logging without gaps: Page 2 of 4

July 29, 2011 //By Jochen Neuffer, Vector Informatik
Data logging without gaps
In order to simulate real situations for the communication networks in a vehicle it is necessary to perform extensive test drives in a real environment. Large amounts of data need to be acquired, recorded and, afterwards, accessed. Here is how this can be achieved.
installed. Often they are mounted at very inaccessible points, e.g. under a seat or behind a trim panel in the cargo space, and they may be inaccessible because of other instrumentation. Therefore, it is advantageous if the test engineer can use a UMTS or WiFi wireless connection to read out data from a logger.  As an alternative, it should also be possible to read out data directly via USB or by swapping out the memory medium. To permit clear traceability of certain driving situations to a specific error pattern in later offline analysis and troubleshooting, the test driver has the option of recording audio comments and camera images along with the regular data during the test drive. In parallel, GPS data can be added to the bus communication for geographic reference. After logging, the data is typically converted on the PC, so that it can be analyzed in other programs such as CANoe, CANalyzer or CANape.

Test fleets need special data loggers

At first glance, it would seem reasonable to use a notebook-based solution for in-vehicle logging. Together with a suitable network interface the notebook should be able to offer all required capabilities, since functionality can be implemented in software. However, commercially available notebooks cannot handle the required temperature range. Furthermore, the system must first be booted, which takes some time – even with fast notebooks. This implies another requirement for data loggers: short startup times. Data must be acquired quickly enough for the first message on the bus to be logged. All of the noted requirements are fulfilled by special fleet loggers such as devices of Vector's GL3000/GL4000 logger product line (Figure 1). Their extended temperature range also makes it possible to use them under extreme environmental conditions. These special fleet loggers also have a real-time clock, ensuring clear time references for the acquired data. 

 Figure 1: Special data loggers for in-vehicle use need a rugged, robust design


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