Characterizing the physical layer of the differential CAN and CAN FD buses requires an oscilloscope. Keysight’s InfiniiVision 3000T, 4000 and 6000 X-Series oscilloscopes with the automotive software package offer many advanced features and capabilities including:
Keysight’s InfiniiVision Series oscilloscopes utilize hardware-based decoding of the CAN/CAN FD differential bus. Most oscilloscope decoding is based on software Hardware-based decoding provides a virtual real-time update of the decode trace and doesn’t degrade the scope’s waveform update rate (up to 1,000,000 waveforms per second). This enhances the scope’s probability of capturing and displaying infrequent serial bus communication errors, such as error frames or CRC errors.
An oscilloscope eye-diagram provides a composite measure of the overall quality of the physical layer in one simple measurement. All recessive and dominant bits of differential CAN bus are overlaid to show worst-case amplitude and worst-case timing of all bits from all frames. The CAN/CAN FD eye-diagram measurement on Keysight’s InfiniiVision X-Series oscilloscopes not only shows amplitude variations of frames transmitted from various nodes in the system, but it also clearly shows network propagation delays during the arbitration and acknowledgement phases of frames.
Today’s automotive and industrial CAN-based systems utilize multiple buses for control and monitoring. Data within multiple buses sometimes needs to be passed from one bus to another. Keysight’s InfiniiVision X-Series scopes are the only oscilloscopes on the market today that can display time-interleaved decoded data from two buses in the same protocol lister table. The time-interleaved lister display makes it easy to trace data that is perhaps passed from one bus to another. Other scopes on the market can either display one table only, or two tables side-by-side. But even when two tables are displayed side-by-side, it can be very difficult to trace the data transfers between the buses.
Segmented Memory Acquisition with Frame Decoding in a Lister Display Engineers often need to capture multiple and consecutive — yet selective — frames of serial data. For example, capture each consecutive occurrence of CAN frame ID: 07F, without capturing everything in between. Without segmented memory acquisition, the alternative is to use a scope with extremely deep memory, and then wade through all that memory after capturing a very long record that includes all frames (not just selective frames). This can be costly, slow, and difficult. Using Agilent’s InfiniiVision Series oscilloscopes, engineers can set up the scope to capture up to 1000 segments (frames) with precise time-tagging between each frame, and then review them individually with automatic decoding (time-correlated decode trace AND lister).
Keysight Technologies’ InfiniiVision X-Series oscilloscopes come in various bandwidth models ranging from 100 MHz up to 6 GHz. To learn more about these oscilloscopes and how they can be used to characterize and debug the physical layer of the differential CAN bus, go to www.keysight.com.