CAN Comfort waveform testing can help technicians examine communication activity between vehicle control units during automotive maintenance. In the Volkswagen PASSAT B7 example described by OWON, vehicle communication uses two CAN field-bus categories: CAN DRIVE and CAN CONFORT. Communication between control units and sensors or actuators may also use the LIN field-bus.
Observing a signal is not, by itself, a complete diagnosis. It is one part of a structured maintenance process that should also consider the vehicle circuit arrangement, the selected measurement point, and the operating state of the network. A tablet oscilloscope provides a visual way to capture and review waveform behavior at the test location.
CAN Comfort measurement on Volkswagen PASSAT B7
For the PASSAT B7 example, the measurement point is set at the driver-side door control unit. The captured signal is then viewed on the display of the TAO3104A. This approach focuses on the CAN CONFORT field-bus, separating the observation from the CAN DRIVE network discussed in a related application context.
Before making any interpretation, technicians should identify the bus line being observed and the vehicle state at the time of capture. Comparing an active communication condition with a sleep condition can provide useful context for the waveform shown on screen. The source example also advises removing the ignition key after measurement is complete.
Reported CAN Comfort waveform observations
OWON reports the following values from the displayed captured signal in this PASSAT B7 application. These readings are specific to the example and should be treated as observed results rather than universal reference values for every vehicle or network condition.
- When CAN_H changes from 0 V to 3.9 V, the reported average voltage is 0.9 V.
- When CAN_L changes from 5 V to 1.14 V, the reported average voltage is 4.1 V.
- The source notes that CAN_L can operate as a single bus.
- In the reported sleep state, CAN_H remains at 0 V while CAN_L remains at 11 V.
These observations illustrate why waveform capture can be valuable in automotive electronics work. Rather than relying only on a static value, a technician can review signal transitions and compare the displayed condition with the expected operating state of the circuit under test.
OWON TAO3000 series features for bus observation
The 4-channel TAO3000 Series Tablet Oscilloscope is specified with bandwidth up to 120 MHz, a maximum real-time sampling rate of 1 GSa/s, 14-bit vertical resolution, a 40M record length, and a waveform refresh rate of 75,000 wfms/s. OWON also lists low base noise for small-signal capture, an 8-inch 800 × 600 multi-point touch screen, and USB host, USB device, LAN, and optional Wi-Fi connectivity.
For triggering and serial-bus work, the TAO3000 series supports Edge, Video, Pulse, Slope, Runt, Windows, Timeout, I2C, SPI, RS232/UART, CAN, and Nth Edge trigger modes. Serial-bus decoding is available for I2C, SPI, RS232/UART, and CAN. The series also supports mathematical functions including FFT, FFTrms, Intg, Diff, Sqrt, user-defined functions, and digital filtering options.
Two-channel option with multimeter functions
The 2-channel TAO3000 Series Tablet Oscilloscope combines a DSO and a built-in 4½-digit multimeter. Its multimeter interface can appear on the same screen as the oscilloscope interface. The multimeter data logging function can record data over an extended period and export it to a CSV file.
For CAN Comfort waveform testing, the appropriate instrument configuration depends on the measurement task, the required channels, and the signal information that needs to be captured. Reviewing waveform behavior carefully and following suitable vehicle service procedures remain essential throughout the maintenance process.
