FAQ 561: Common Causes of Invisible CAN Messages and How to Fix Them

Question

What configurations should I verify if CAN messages are not being logged or displayed?

Solution

CAN messages might not appear due to missing configurations in VEOS or SystemDesk, incorrect network mapping, or CAN controller settings such as wake-up, CAN FD, or hardware filters.

Detailed Troubleshooting Sections:

VEOS Checks:

In VEOS, message visibility issues are often related to improper mapping of the signals/Network.

1. To confirm if the communication channels are sending and receiving the signals, enable Bus logging in VEOS, under preferences. A PCAPNG file is generated, which could be visualized in Wireshark.

This confirms, if the CAN Cluster is sending or receiving the signals.

2. Check if there is proper mapping enabled in the Network topology with the BSC or Plant Model. Without proper connection, a few signals might not get the wake-up signals.

SystemDesk Checks:

In SystemDesk, incorrect CAN stack configuration can prevent messages from being transmitted or observed.

1. General CAN Settings

Enable CanMultiplexedTransmission (for multiplexed messages)

2. CAN Controller Settings
If the code requires flag settings in ID, ensure that both are enabled: 

• CanSetExtendedCanFrameIdFlag
• CanSetCanFdFrameIdFlag (for CAN FD messages)
   

3. Wake-Up Handling
Enable CanWakeSupport if signals depend on wake-up
 

4. Hardware Resource Configuration
Check CanHwObjectCount 

• Increase (>10) if the CAN busy status remains.

5. Filtering
Verify CanHwFilter settings 

• Incorrect filters might block messages

6. DIO / Hardware Dependency
If CAN operational requires an I/O signal, check I/O inputs and ensure the required DIO port is set to HIGH.

• Required for CAN channel wake-up in some setups

CanTrcv_EnterCritical();

// Should be STD_HIGH to work
CanTrcvSTB = Dio_ReadChannel(CanTrcv_30_Tja1043_GetPinSTBofDioConfiguration(CanTrcvIndex));
CanTrcvEN = Dio_ReadChannel(CanTrcv_30_Tja1043_GetPinENofDioConfiguration(CanTrcvIndex));

If this does not work, contact dSPACE Product Support (support@dspace.de)

User documentation

For the detailed explanation on CAN Configuration, refer to the document “Creating Code-Based V ECUs - dSPACE”