32-bit Modbus write values are not writing correctly

32-bit Modbus write values are not writing correctly


When a modbus AO is created and set to 32-bit real swapped, the correct value is not seen at the modbus device.

  • 1000 is written and 1000 is shown correctly at the Modbus device.
  • 1001, 1002, 1003 are written but 1000 is seen at the Modbus device.
  • 1004 is written and 1004 shows correctly at the Modbus device.
  • And so forth. The larger the number, the larger the error increase.

Product Line

EcoStruxure Building Operation


  • Enterprise Server (ES)
  • Automation Server (AS)


When 32 bit real swapped is selected

Further down the configuration page, the write function code defaults to "06". 06 is to set a single 16-bit register write and this needs to be changed.


Use the drop down tab and set the function code to "16". 16 is to preset multiple registers i.e. 2 off consecutive 16-bit registers or a 32-bit register.

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