Write to Read-Only Register

What does #23 mean?

The Destination Device (inverter) rejected a write command because the targeted register is designated as read-only. This fault occurs when the Modbus command attempts to alter a parameter or status value that the inverter only permits to be read, not written, thereby protecting internal state and configurations.

• The Modbus function code (e.g., 'Write to Holding Register') was used for a register that is defined as read-only in the inverter's Modbus communication data lists.
• An incorrect register address (S+2) was specified, accidentally targeting a read-only register instead of a writable one.

Click steps to track your progress.

1. 1

   Verify the Modbus function code (S+1 lower byte) and the Register address (S+2) in the CMND instruction operand. Ensure a read function (e.g., #03) is used for read-only registers.

2. 2

   Refer to '8-9 Modbus Communication Data Lists' in the Multi-function Compact Inverter MX2 Series Type V1 User’s Manual (Cat. No. I585) to confirm the read/write permissions for the target register.