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visastatus

Check status of VISA resource

    Description

    example

    tf = visastatus(v) returns 1 (true) if the VISA resource v has requested and is ready for service and returns 0 (false) if it has not requested service.

    [tf,status] = visastatus(v) returns the full status byte register containing event information.

    Examples

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    Create a connection to an oscilloscope using the VISA-GPIB interface.

    v = visadev("GPIB0::11::INSTR");

    Configure the oscilloscope to request service when a command error occurs.

    writeline(v,"*CLS");
    writeline(v,"*PSC 0");
    writeline(v,"*ESE 0");
    writeline(v,"DESE 0");
    writeline(v,"*SRE 32");

    Send the "Volt?" query to the oscilloscope. Since it is an invalid command, a command error occurs.

    writeline(v,"Volt?");

    Check whether the oscilloscope has requested service.

    visastatus(v)
     
    ans =
     
      logical
     
       1

    Since a command error occurs when you send the "Volt?" command, the oscilloscope has requested service.

    Input Arguments

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    VISA resource, specified as a visadev object.

    Example: visastatus(v) checks the status of the VISA resource service request.

    Output Arguments

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    True or false result, returned as a 1 or 0 of data type logical.

    Data Types: logical

    Status byte register, returned as a positive integer from 0 to 255. You can convert this value to its binary value using dec2bin and interpret each bit as information about the VISA resource.

    Each bit is associated with a type of event. For example, bit 6 (RQS) indicates the status of the VISA resource service request.

    Status Byte Register Bits

    Bit

    Label

    Description

    0-3

    Instrument-specific summary messages.

    4

    MAV

    The Message Available bit indicates if data is available in the Output Queue. MAV is 1 if the Output Queue contains data. MAV is 0 if the Output Queue is empty.

    5

    ESB

    The Event Status bit indicates if one or more enabled events have occurred. ESB is 1 if an enabled event occurs. ESB is 0 if no enabled events occur. You enable events with the Standard Event Status Enable Register.

    6

    MSS

    The Master Summary Status summarizes the ESB and MAV bits. MSS is 1 if either MAV or ESB is 1. MSS is 0 if both MAV and ESB are 0. This bit is obtained from the *STB? command.

    RQS

    The Request Service bit indicates that the instrument requests service. This bit can be used for serial polling.

    7

    Instrument-specific summary message.

    Data Types: double

    Introduced in R2021a