Writes values to one or more bits of a holding register.


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Inputs/Outputs

  • cModbus_Masterlvclass.png Modbus master in —

    Modbus master in specifies the reference to the Modbus master instance. Use the Create Master Instance VI to create a Modbus master instance.

  • cu16.png address —

    address specifies the holding register address to which you want to write the values. Valid values are between 0 and 65,535, where 65,535 is the maximum number.

    The address that this VI writes is 0-based, meaning that the address numbering convention for the Modbus slave starts at 0.

  • 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 AND mask —

    AND mask specifies the AND mask you use to write bits of a holding register.

    Refer to the Details section of this topic for examples of specifying the AND mask.

  • cu16.png OR mask —

    OR mask specifies the OR mask you use to write bits of a holding register.

    Refer to the Details section of this topic for examples of specifying the OR mask.

  • iModbus_Masterlvclass.png Modbus master out —

    Modbus master out returns a duplicate of Modbus master in.

  • ierrcodeclst.png error out —

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

    • Mask Write Holding Register Details

    The Mask Write Holding Register VI uses the following algorithm to calculate the value to write to individual bits of a holding register:

    updated value = (current value AND AND mask) OR (OR mask AND (NOT AND mask))

    Based on the previous algorithm, you can specify values for AND mask and OR mask according to the following rules:

    • To write a bit, specify 1 for AND mask for this bit. If you want to mask a bit, specify 0 for AND mask for this bit. When you specify 0 for AND mask, the value of the bit does not change regardless of what value you specify for OR mask.
    • After you specify 0 for AND mask for a bit, you can specify 0 for OR mask to change the value of this bit to 0, regardless of the current value of the bit.
    • After you specify 0 for AND mask for a bit, you can specify 1 for OR mask to change the value of this bit to 1, regardless of the current value of the bit.