NI-VCOM restbus simulation supports different transmission modes. The AUTOSAR files already define the supported transmission modes. However, you must perform additional configuration using the RBSConfig Tool if you use .dbc or .ldf files.

The interaction layer converts the signal-based access of higher applications to the message-based transmission method of the bus system. Every message in a bus system is assigned a specific transmission mode, which is listed in the .dbc or AUTOSAR-XML file. The transmission mode defines the intervals and conditions the message transmits under. Messages can send with different transmission modes. NI-VCOM supports the following transmission modes:

  • Cyclic—The message sends periodically.
    Figure 2. Cyclic Transmission Mode

    Cyclic Transmission Mode

  • Spontaneous—The message always sends when at least one of its signals changes its value.
    Figure 3. Spontaneous Transmission Mode

    Spontaneous Transmission Mode

  • Cyclic if active—The message sends periodically if at least one of its signals differs from its inactive value. The message sends again n+1 times as soon as the last signal is inactive (stop messages). n is defined when all signals become default.
    Figure 4. Cyclic if Active Transmission Mode

    Cyclic if Active Transmission Mode

  • Spontaneous with minimum delay—The message always sends under the following conditions:
    • At least one of its signals changes its value.
    • The last transmission is sent at least the specified interval ago.
    Figure 5. Spontaneous with Minimum Delay Transmission Mode

    Spontaneous with Minimum Delay Transmission Mode

  • Cyclic and spontaneous—This transmission type is a combination of the cyclic and spontaneous transmission types.
    Figure 6. Cyclic and Spontaneous Transmission Mode

    Cyclic and Spontaneous Transmission Mode

  • Cyclic and spontaneous with minimum delay—In principle, this transmission mode is the same type as cyclic and spontaneous but with a minimum delay. Fulfilling the delay time has a higher priority than fulfilling the cycle time.
    Figure 7. Cyclic and Spontaneous with Minimum Delay Transmission Mode

    Cyclic and Spontaneous with Minimum Delay Transmission Mode

  • Spontaneous with repetition and minimum delay—If a signal of a message with this transmission type changes, the message sends with a minimum delay of t_min. After that, the message repeats for n times with a cycle time of t. The complete number of sent messages is n+1. Fulfilling the delay time has a higher priority than fulfilling the repetition cycle time.
    Figure 8. Spontaneous with Repetition and Minimum Delay Transmission Mode

    Spontaneous with Repetition and Minimum Delay Transmission Mode

  • Cyclic if active and spontaneous with minimum delay—As soon as at least one signal from this message is active, the message sends periodically. If a signal changes, the message sends immediately, taking into account the minimum interval. Fulfilling the delay time has a higher priority than fulfilling the cycle time.
    Figure 9. Cyclic if Active and Spontaneous with Minimum Delay Transmission Mode

    Cyclic if Active and Spontaneous with Minimum Delay Transmission Mode

  • Cyclic if active fast—The message sends periodically using the following different cycle times:
    • Cycle time for the inactive state
    • Cycle time for the active state
    At least one signal must be active.The minimum delay time is considered while the transmission goes from the inactive state to the active state. The same is true when the transmission goes from the active to inactive state. Fulfilling the delay time has a higher priority than fulfilling the cycle time.
    Figure 10. Cyclic if Active Fast Transmission Mode

    Cyclic if Active Fast Transmission Mode

  • Event and periodic—The message repeats n times on any event. If no event exists, the message is sent by t_1. If something changes, the message is sent by t_2 and repeated three times.
    Figure 11. Event and Periodic Transmission Mode

    Event and Periodic Transmission Mode

    • The following table shows which values are relevant to the different types of transmission:
    Table 4. Relevant Values for Different Transmission Modes
    SendType CycleTime CycleTimeActive DelayTime NumOfRepetitions
    Cyclic Relevant — — —
    Spontaneous — — — —
    SpontaneousWD — — Relevant —
    CyclicAndSpontaneous Relevant — — —
    CyclicAndSpontaneousWD Relevant — Relevant —
    SpontaneousWithRepetitionWD Relevant — Relevant Relevant
    CyclicIfActiveAndSpontaneousWD — Relevant Relevant —
    CyclicIfActive — Relevant — Relevant
    CyclicIfActiveFast Relevant Relevant Relevant —
    EventAndPeriodic Relevant Relevant — Relevant