9 CAN Monitoring

The Komodo CAN Duo Interface is a CAN interface capable of active CAN data transmission as well as non-intrusive CAN bus monitoring.

The Komodo CAN Duo Interface has two independent, customizable CAN channels along with eight configurable GPIOs. The Komodo interface also has two virtual USB ports (via a single physical USB port).

The two CAN channels make simultaneous communication on and/or monitoring of two separate CAN buses possible using a single Komodo CAN Duo Interface. GPIO, General Purpose IO, allows users to synchronize external logic with a CAN channel, as well as output events to external devices, such as oscilloscopes. The two virtual USB ports allow users to communicate with a single Komodo interface simultaneously from two software applications.

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9.1 Performing a CAN Capture

Here are the steps for starting a CAN capture.

1. Start the Total Phase Data Center application.

2. Connect the Komodo CAN Duo Interface to the analysis computer. Make sure that the green indicator LED has illuminated.

3. Connect the Komodo CAN DUO Interface to the CAN bus.The Komodo CAN Duo Interface features two connectors for each CAN channel: a common DB-9 connector and a block screw terminal which wires can easily connect to. Ensure the CAN bus is properly terminated, otherwise the Komodo is saturated with CAN errors.

4. Click Connect to Analyzer… in the toolbar and connect to a Komodo CAN Duo Interface.

5. Select CAN from the Protocol Lens pull-down menu under the Transaction Window.

6. Click Device Settings… in the toolbar and set the CAN capture settings. Make sure CAN is selected in the Capture Protocol pull-down menu.

7. Connect the Komodo CAN Duo Interface to the target device.

8. Click the Run Capture button to start the data capture. Once the capture has started, the capture indicator will turn green and an informational transaction will appear in the Transaction window which notes when the capture was started.

9. To stop the capture, click on the Stop button.

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9.2 CAN Device Settings

The CAN device settings described below can be configured in the Device Settings dialog (Figure 101). To open this dialog, click on the Device Settings… button.

The Device Settings dialog can also be accessed through Analyzer | Device Settings….

Figure 101: CAN Tab of the Device Settings Dialog

Monitor channel

Monitor channel checkbox enables monitoring selected channel (A or B) on the connected Komodo CAN Duo Interface port. Data Center software can monitor either or both of the channels.

Make active node

Make active node checkbox enables packet ACKing on the corresponding channel on the connected Komodo port. When the box is checked, the application will acquire the appropriate Control feature from the Komodo port. When the box is unchecked, the port will act as a passive monitor (listen-only) on the CAN bus. For more information, refer to the Komodo CAN Duo Interface datasheet. This option is valid only when Monitor channel is checked for this channel.

Include packets from this unit

If checked, CAN traffic generated by this Komodo unit will be includes

Configure Bus Settings

Configure Bus Settings checkbox enables congiguring the corresponding channel on the connected Komodo port. When the box is checked, the application will acquire the appropriate Config feature from the Komodo port. When the box is unchecked, all configuration options will be disabled on this channel. This option is valid only when Monitor channel is checked for this channel. Only one application can configure the bus settings at a time.

Target power

It is possible to power one or more downstream CAN nodes using the V+ pin. The Komodo CAN Duo Interface can source a maximum of 73mA per CAN channel with V+.

To enable or disable target power on corresponding channel, check or uncheck the box in the Settings window. This option is valid only when Monitor channel and Acquire config resource are checked for this channel.

Bitrate (Hz)

The bitrate can be manually configured for each channel by entering a bitrate value in the Bitrate Field of the dialog. The resulting bitrate may slightly differ from the entered value, as only certain discrete bitrates are permitted. The application will set the bitrate to the value nearest the entered bitrate.

The bitrate can be set automatically for each channel by pressing the Auto Bitrate Button . Once the bitrate detection operation completes, the result will appear in the corresponding Bitrate Field.

These options are valid only when Monitor channel and Acquire config resource are checked for this channel.

Enable GPIO Configuration

Enabled GPIO Configuration checkbox enables configuring GPIO pins. When the box is checked, the application will acquire GPIO Control feature from the Komodo port. When the box is unchecked, configuring GPIO pins is disabled. Only one application can configure the GPIO interface at a time.

Configure GPIO button opens the Komodo GPIO configuration dialog.

Komodo GPIO configuration

Figure 102: Komodo GPIO configuration Dialog

The Komodo GPIO configuration dialog offers a way to configure general purpose input and output (GPIO) pins. Each of the pins labeled with IN 1, IN 2, IN 3, IN 4 can be configured as an input by dragging one of the inputs from Configure Input section and dropping it on one of these pins. Each of the pins labeled with OUT 1, OUT 2, OUT 3, OUT 4 can be configured as an output by dragging one of the outputs from Configure Output section and dropping it on one of these pins. The various options for each pin type are described below.

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Configure Input

Digital inputs allow users to synchronize external logic with a CAN channel. Whenever the state of an enabled digital input changes, an event will be sent to the analysis PC and displayed in the transaction log.

• Rising Edge - Report change on rising edge.

• Falling Edge - Report change on falling edge.

• Both Edges - Report change on both edges.

The digital input options are as follows:

Bias

Specify a voltage bias for an input pin.

• Pull-Down - Pulls down input voltage using high impedance resistor to GND.

• Pull-Up - Pulls up input voltage using high impedance resistor to 3.3V.

• Hi-Z - No modification to input voltage.

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Configure Output

Digital outputs allow users to output events to external devices. A common use for this feature is to trigger an oscilloscope or logic analyzer to capture data. The output pins can be activated on the various conditions below. Refer to the Komodo datasheet for details on the output signal characteristics and refer to the CAN specification for details on the different error types.

• Any Error - Output pulse on any error.

• Bit Error - Output pulse on bit error.

• Form Error - Output pulse on form error.

• Stuff Error - Output pulse on stuff error.

• Other Error - Output pulse on other error.

The digital output options are as follows:

Channel

Specify a source channel for an error activated output pin.

• A - Active on CAN A error.

• B - Active on CAN B error.

• Both - Active on CAN A or B error.

Drive

Specify the voltage drive for an output pin.

• Normal - Active is 3.3V; Inactive is GND.

• Inverted - Active is GND; Inactive is 3.3V.

• Open Drain - Active is GND; Inactive is floating.

• +Pullup - Equivalent to Open Drain with a high impedance pullup.

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Defaults

Set the default configuration for all of the pins. This will configure IN pins as inputs with pull-downs that report changes on both edges and OUT pins as outputs that activate on any error.

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9.3 Transaction Window

The CAN Transaction window (Figure 103) displays all the transactions that were captured on the CAN bus in real time. When a transaction is selected in the Transaction window, detailed information about that transaction is displayed in the Info pane.

Figure 103: CAN Transaction Window

For a general description of the Transaction window, see Section 5.1. The general description encompasses the behavior of the CAN Transaction window, with the following modifications:

Ch
The channel on which the packet or event occurred.

Error codes (Err)
Error codes listing abnormal conditions that occurred while capturing the transaction. See Table 2 for the possible error codes. In addition, there are several CAN specific error codes as described in Table 8.

Bitrate
The bitrate of the CAN bus in kHz.

ID
The ID of the source CAN node of the CAN packet. When a packet is marked as RTR, the ID, instead, corresponds to the destination CAN node (the requestee).

DLC
DLC (Data Length Code) is the specified number of bytes transmitted in a single CAN packet.

Data
The data payload for CAN packets, and a textual description for CAN events, errors, and capture events.

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9.4 Filtering a CAN Capture

The following is a description of the parameters that are specific to the CAN protocol. For a description of the General parameters, or for information on how to operate the Filter pane, refer to Section 5.5.

Figure 104: CAN Filter Pane

ID
An ID that filters the transactions based on the ID of the source CAN node.

Extended ID
An extended ID that filters the transactions based on the extended ID of the source CAN node.

Data Length Code
An iteger that filters the transactions based on the DLC field.

Traffic
Filters traffic that originated from the Komodo or traffic that was observed from other sources.

Channel
Filters transactions to include packets and events that occured only on the selected channels.

Error States
Filters instances of entry into one of the following error states: [ Active, Passive, Warning, or Bus Off]

Bus Event
Filters traffic that is considered a bus event such as a change in bitrate.

GPIO Event
Filters traffic that is considered a GPIO event (Digital Input).

Arbitration Loss
Filters instances where the Komodo is aware that it has lost an arbitration event.

Data Frame
Filters Data Frames from view.

Remote Frame
Filters Remote Frames from view.

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9.5 Bus Pane

Bus
Clicking on any device in the Bus Pane will display bus specific statistics information in the stats pane and allow filtering according to that specific bus.

Device
Clicking on any device in the Bus Pane will display device specific statistics information in the stats pane.

Transaction Type
Clicking on a transaction type (Data/Remote) in the Bus Pane will not display data in the statistics pane, but will allow filtering according to the transaction type for the device.

Traffic Origin
Clicking a given traffic origin (Komodo/Observed) in the Bus Pane will display statistics and allow to filter traffic corresponding to the bus-device-transaction-origin.