Creates a serial or TCP Modbus master instance. You must manually select the polymorphic instance to use.

You can use the Modbus master instance to perform read and write operations on Modbus slaves. The default read and write operation timeout is 5,000 ms. You can use the Property Node or the Set Timeouts VI to change the timeout.

Use the pull-down menu to select an instance of this VI.


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Inputs/Outputs

  • cenum.png serial type —

    serial type specifies the type of data transmission through serial ports.

  • cu8.png unit ID —

    unit ID specifies the identification of the Modbus slave with which you want to communicate. The Modbus slave can be a Modbus slave you create or a third-party Modbus slave. If you want to communicate with a third-party Modbus slave, check the documentation for the Modbus slave to find its unit ID.

  • cvsrn.png VISA resource name —

    VISA resource name specifies the resource you want to open.

  • cu32.png baud rate (9600) —

    baud rate specifies the baud rate of the Modbus slave with which you want to communicate. The Modbus slave can be a Modbus slave you create or a third-party Modbus slave. If you want to communicate with a third-party Modbus slave, check the documentation for the Modbus slave to find its baud rate. The default is 9,600.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • cu16.png parity (Even) —

    parity specifies the parity of the Modbus slave with which you want to communicate. The Modbus slave can be a Modbus slave you create or a third-party Modbus slave. If you want to communicate with a third-party Modbus slave, check the documentation for the Modbus slave to find its parity.

  • cu16.png flow control (None) —

    flow control specifies the flow control of the Modbus slave with which you want to communicate. The Modbus slave can be a Modbus slave you create or a third-party Modbus slave. If you want to communicate with a third-party Modbus slave, check the documentation for the Modbus slave to find its flow control.

  • iModbus_Masterlvclass.png serial master instance —

    serial master instance returns a serial Modbus master instance.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • Examples

    Refer to the following VIs for examples of using the Create Master Instance VI:

    • labview\examples\Data Communication\Modbus\ModbusLibrary\Modbus Library.lvproj
    • labview\examples\Data Communication\Modbus\Redundant Modbus Masters\Redundant Modbus Masters.lvproj