Reads data from a session as an array of Ethernet frames. The session must use an Ethernet interface and a mode of Frame Input Stream.


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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.

  • 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 timeout of 0.

    This input is optional. The default value is –1.

  • 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 Ethernet) 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 Ethernet) VI waits indefinitely for number to read frame values.

    If timeout is zero, the XNET Read (Frame Ethernet) VI does not wait and immediately returns all available frame values up to the limit specified by number to read.

    This input is optional. The default value is 0.0.

  • 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 that the session receives. The elements of each cluster are specific to the Ethernet protocol.

  • iatrn.png local timestamp —

    local timestamp is a timestamp using XNET local time. The timestamp uses the LabVIEW absolute timestamp type.

    The timestamp point in the Ethernet frame occurs at the beginning of the first symbol following the start of frame delimiter.

    The location of the timestamp point depends on the Port Mode of the session interface. When Port Mode is Direct, the location of the timestamp point corresponds to time synchronization protocols, using the reference plane marking the boundary between the port's connector (copper wire) and PHY. When Port Mode is Tap, the location of the timestamp point is the midpoint between the connector/PHY reference plane of this session's interface and the connector/PHY reference plane of the tap partner.

  • iatrn.png network timestamp —

    network timestamp is a timestamp using network time (clock of the network's time synchronization protocol, such as IEEE Std 802.1AS). The timestamp uses the LabVIEW absolute timestamp type.

    The timestamp point in the Ethernet frame occurs at the beginning of the first symbol following the start of frame delimiter.

    The location of the timestamp point depends on the Port Mode of the session interface. When Port Mode is Direct, the location of the timestamp point corresponds to time synchronization protocols, using the reference plane marking the boundary between the port's connector (copper wire) and PHY. When Port Mode is Tap, the location of the timestamp point is the midpoint between the connector/PHY reference plane of this session's interface and the connector/PHY reference plane of the tap partner.

  • i1du8.png frame data —

    data returns an array of LabVIEW clusters.

    Each array element corresponds to a frame that the session receives. The elements of each cluster are specific to the Ethernet protocol.

  • iu32.png fcs —

    fcs is the IEEE Std 802.3 Frame Check Sequence (FCS) that was received with the frame.

  • iu16.png type —

    type is the type of Ethernet frame. It is a ring (enumerated list) with the following values:

  • ibool.png network synced? —

    network synced? contains the value of the Synced property at the time that both timestamps are acquired, to specify whether the network timestamp is synchronized to the network (true) or not (false).

  • ibool.png receive? —

    receive? indicates whether the frame occurred due to receive (true) or not (false).

    For XNET Read on the monitor path:

    • When Port Mode of this session's interface is Direct, this flag is true when a frame is received on the interface.
    • When Port Mode of this session's interface is Tap, the value true indicates that the frame was received by this interface, and will be transmitted on the tap partner.

    For XNET Read on the endpoint path, this flag is always true.

  • ibool.png transmit? —

    transmit? indicates whether the frame occurred due to transmit (true) or not (false).

    For XNET Read on the monitor path:

    • When Port Mode of this session's interface is Direct, the monitor path echoes each transmit that was submitted to XNET Write on the endpoint path.
    • When Port Mode of this session's interface is Tap, the value true indicates that the frame was received by the tap partner and transmitted on this interface (i.e., not an echo of Write).

    For XNET Read on the endpoint path, this flag is always false.

  • ibool.png error? —

    error? indicates that an error occurred during reception/transmission of the frame (false = good frame, true = bad frame).

  • 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 —

  • i1du8.png payload —

    • Description

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