Reads data from a session as an array of FlexRay frames. The session must use a FlexRay interface and a mode of Frame Input Stream, Frame Input Queued, or Frame Input Single-Point.


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Inputs/Outputs

  • cgenclassrntag.png session in —

    session in is the session to read. This session is selected from the LabVIEW project or returned from the XNET Create Session VI. The session mode must be Frame Input Stream, Frame Input Queued, or Frame Input Single-Point.

  • ci32.png number to read (-1) —

    number to read is the number of frame values desired. If number to read is positive (or 0), the data array size is no greater than this number. If number to read is negative (typically –1), all available frame values are returned. If number to read is negative, you must use a timeout of 0. This input is optional. The default value is –1. If the session mode is Frame Input Single-Point, set number to read to either –1 or the number of frames in the session list. This ensures that the XNET Read (Frame FlexRay) VI can return the current value of all session frames.

  • cdbl.png timeout (0) —

    timeout is the time to wait for number to read frame values to become available. The timeout is a LabVIEW relative time, represented as 64-bit floating-point in units of seconds. If timeout is positive, the XNET Read (Frame FlexRay) VI waits for number to read frame values, then returns that number. If the values do not arrive prior to the timeout, an error is returned. If timeout is negative, the XNET Read (Frame FlexRay) VI waits indefinitely for number to read frame values. If timeout is zero, the XNET Read (Frame FlexRay) VI does not wait and immediately returns all available frame values up to the limit number to read specifies. This input is optional. The default value is 0.0. If the session mode is Frame Input Single-Point, you must leave timeout unwired (0.0). Because this mode reads the most recent value of each frame, timeout does not apply.

  • cerrcodeclst.png error in (no error) —

    The error in cluster can accept error information wired from VIs previously called. Use this information to decide if any functionality should be bypassed in the event of errors from other VIs. The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

  • igenclassrntag.png session out —

    session out is the same as session in, provided for use with subsequent VIs.

  • i1dcclst.png data —

    data returns an array of LabVIEW clusters. Each array element corresponds to a frame the session receives. For the Frame Input Single-Point and PDU Input Single-Point session modes, the order of frames/payload in the array corresponds to the order in the session list. The elements of each cluster are specific to the FlexRay protocol. The cluster elements are:

  • iatrn.png timestamp —

    timestamp represents the absolute time when the XNET interface received the frame (end of frame), accurate to microseconds. The timestamp uses the LabVIEW absolute timestamp type. While the NI-XNET FlexRay interface is communicating (integrated), this timestamp is normally derived from FlexRay global time, the FlexRay network timebase. Under this configuration, the timestamp does not drift as compared to the FlexRay global time (the XNET Read (State Flexray Cycle Macrotick) VI), but it may drift relative to other NI hardware products and the LabVIEW absolute timebase. If you prefer to synchronize this timestamp to other sources, you can use the XNET Connect Terminals VI to change the source of the Master Timebase terminal.

  • i1du8.png payload —

    payload is the array of data bytes for FlexRay frames of type FlexRay Data or FlexRay Null. The array size indicates the received frame value payload length. According to the FlexRay protocol, this length range is 0–254. For PDU session modes, only the payload for the particular PDU is returned, not the entire frame.

  • iu16.png slot —

    slot specifies the slot number within the FlexRay cycle.

  • iu8.png type —

    type is the frame type (decimal value in parentheses):

  • iu8.png cycle count —

    cycle count specifies the cycle number. The FlexRay cycle count increments from 0 to 63, then rolls over back to 0.

  • ibool.png startup? —

    startup? is a Boolean value that specifies whether the frame is a startup frame (true) or not (false).

  • ibool.png sync? —

    sync? is a Boolean value that specifies whether the frame is a sync frame (true) or not (false).

  • ibool.png preamble? —

    preamble? is a Boolean value that specifies the value of the payload preamble indicator in the frame header. If the frame is in the static segment, preamble? being true indicates the presence of a network management vector at the beginning of the payload. The XNET Cluster FlexRay:Network Management Vector Length property specifies the number of bytes at the beginning. If the frame is in the dynamic segment, preamble? being true indicates the presence of a message ID at the beginning of the payload. The message ID is always 2 bytes in length. If preamble? is false, the payload does not contain a network management vector or a message ID.

  • ibool.png ch A —

    chA is a Boolean value that specifies whether the frame was received on channel A (true) or not (false).

  • ibool.png ch B —

    chB is a Boolean value that specifies whether the frame was received on channel B (true) or not (false).

  • ibool.png echo? —

    echo? Is a Boolean value that determines whether the frame was an echo of a successful transmit (true) or received from the network (false). This value is true only when you enable echo of transmitted frames by setting the XNET Session Interface:Echo Transmit? property to true. Frames are echoed only to a session with the Frame Input Stream mode.

  • ierrcodeclst.png error out —

    The error out cluster passes error or warning information out of a VI to be used by other VIs. The pop-up option Explain Error (or Explain Warning) gives more information about the error displayed.

  • i1dcclst.png unused payloads —

    payload is the array of data bytes for FlexRay frames of type FlexRay Data or FlexRay Null. The array size indicates the received frame value payload length. According to the FlexRay protocol, this length range is 0–254. For PDU session modes, only the payload for the particular PDU is returned, not the entire frame.

  • i1du8.png payload —

    payload is the array of data bytes for FlexRay frames of type FlexRay Data or FlexRay Null. The array size indicates the received frame value payload length. According to the FlexRay protocol, this length range is 0–254. For PDU session modes, only the payload for the particular PDU is returned, not the entire frame.

    • Description

    The data represents an array of FlexRay frames. Each FlexRay frame uses a LabVIEW cluster with FlexRay-specific elements.

    The FlexRay frames are associated to the session list of frames as follows:

    • Frame Input Stream: Array of all frame values received (list ignored).
    • Frame Input Queued: Array of frame values received for the single frame specified in the list.
    • Frame Input Single-Point: Array of single frame values, one for each frame specified in the list.
    • PDU Input Queued: Array of frame (PDU payload) values received for the single PDU specified in the list. This mode is similar to Frame Input Queued.
    • PDU Input Single-Point: Array of single frame ( PDU payload) values, one for each PDU specified in the list. This mode is similar to Frame Input Single-Point.

    Due to issues with LabVIEW memory allocation for clusters with an array, this XNET Read VI instance can introduce jitter to a high-priority loop on LabVIEW Real-Time (RT). The XNET Read (Frame Raw) VI instance provides optimal performance for high-priority loops.