Industrielle styresystemer - Wiki
| Exception Code (Hex) | Name | Meaning |
|----------------------|----------------------------|---------------------------------------------------------------------------------------------------------------------|
| 01 | Illegal Function | The function code received is not allowed for this slave, possibly due to being unimplemented or inappropriate state.|
| 02 | Illegal Data Address | The data address received in the query is not an allowable address for the slave. |
| 03 | Illegal Data Value | A value in the query data field is not allowable for the slave. |
| 04 | Slave Device Failure | An unrecoverable error occurred while the slave attempted the requested action. |
| 05 | Acknowledge | The slave has accepted the request and is processing it, but it needs more time. |
| 06 | Slave Device Busy | The slave is busy processing a long-duration command. |
| 07 | Negative Acknowledge | The slave cannot perform the program function received in the query. |
| 08 | Memory Parity Error | The slave detected a parity error in memory when attempting to read extended memory. |
| 0A | Gateway Path Unavailable | The gateway could not allocate an internal communication path for processing the request. |
| 0B | Gateway Target Device Failed to Respond | No response was obtained from the target device on the network. |
https://www.simplymodbus.ca/exceptions.htm