Modbus Exception: Illegal Data Value

What does 03 hex mean?

This Modbus exception is returned when the master device sends a data value that is outside the permissible range or in an unacceptable format for the specified Modbus address. This means the value attempting to be written is invalid according to the parameter's constraints or data type, preventing a successful write operation.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   If Modbus mapping is enabled, verify the 'Modbus Mapping Scaling' (P221 to P230) settings for proper data conversion and scaling.

2. 4

   Ensure the data resolution (e.g., 0.01 Hz, 0.1%) is correctly applied when sending data.