Reads data from a session of Signal Input XY mode.


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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 Signal Input XY.

  • ci32.png number to read (-1) —

    number to read is the number of values desired. If number to read is positive (or 0), the size of value arrays is no greater than this number. If number to read is negative (typically –1), the maximum number of values is returned. This input is optional. The default value is –1. If number to read values are received for any signal, the XNET Read (Signal XY) VI returns those values, even if the time limit has not occurred. Therefore, to read values up to the time limit, leave number to read unwired (–1).

  • catrn.png time limit (none) —

    time limit is the timestamp to wait for before returning signal values. If time limit is valid, the XNET Read (Signal XY) VI waits for the timestamp to occur, then returns available values (up to number to read). If you increment time limit by a fixed number of seconds for each call to the XNET Read (Signal XY) VI, you effectively obtain a moving window of signal values. If time limit is unwired (invalid), the XNET Read (Signal XY) VI returns immediately all available values up to the current time (up to number to read). This input is optional. The default value is an invalid timestamp. The timeout of other XNET Read VI instances specifies the maximum amount time to wait for a specific number to read values. The time limit of the XNET Read (Signal XY) VI does not specify a worst-case timeout value, but rather a specific absolute timestamp to wait for.

  • 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 signal configured for the session. The order of signals in the array corresponds to the order in the session list. Each cluster contains two arrays, one for timestamp and one for value. For each signal, the size of the timestamp and value arrays always is the same, such that it represents a single array of timestamp/value pairs. Each timestamp/value pair represents a value from a received frame. When signals exist in different frames, the array sizes may be different from one cluster (signal) to another. The cluster elements are:

  • i1datrn.png timestamp —

    timestamp is the array of LabVIEW timestamps, one for each frame received that contains the signal. Each timestamp represents the absolute time when the XNET interface received the frame (end of frame), accurate to microseconds.

  • i1ddbl.png value —

    value is the array of signal values, one for each frame received that contains the signal. Each signal value is scaled, 64-bit floating point. The value array size is the same as the timestamp array size.

  • 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.

    • Description

    You also can use this instance to read data from a session of Signal Input Single-Point mode, although the XNET Read (Signal Single-Point) VI is more common for that mode.

    The data represents an XY plot of timestamp/value pairs for each signal in the session. You can wire the data directly to a LabVIEW XY Graph for display.