4 Interpreting DLT Logs

The previous sections have described setting up on how to start and end logs, what different modes there are and how to trigger a transfer of the logs to another location based on the trigger level of the DLT. How do users interpret the logs from the internal memory?

There are two terminologies, code markers and variables being data logged. Each of these have a way to interpret the logs from the nternal memory of the DLT. The code markers or DLTAGs must be interpreted slightly differently than the variables being data logged or DLREGs.

The internal memory where the logs are being stored are at the base address of the DLT_FIFO_REGS. The internal memory works like a FIFO. When reading from the FIFO_BUF_H, the next log is pushed up. Thus the order in reading from the FIFO matters. The way to read from this memory mapped register is to read the FIFO_BUF_L contents first, then read the FIFO_BUF_H contents next.

Depending on the capture mode, interpreting the log is different. When reading from the FIFO, the first item to look for is the LSB of the lower 32 bits. This provides information on whether this is a code marker (DLTAG) or a logged variable (DLREG). The rest of the information can be decoded through the tables described in the technical reference manual. For this application note, the DLT tool is used to interpret DLT information when the mode is set to capture the time values.