The errors of Modbus data transmission.
| Name | Value | Meaning |
|---|---|---|
| MB_NO_ERROR | 0 | No error. |
| MB_ILLEGAL_FUNCTION | 1 | The function code received by a device is not recognized or accepted. |
| MB_ILLEGAL_DATA_ADDRESS | 2 | The data address (register number) is invalid for a device. |
| MB_ILLEGAL_DATA_VALUE | 3 | The value contained in the data field is invalid. |
| MB_SLAVE_DEVICE_FAILURE | 4 | An error occurs when a device is trying to perform the requested task. |
| MB_ACKNOWLEDGE | 5 | The request from a device has been acknowledged, but a long duration of time will be required to do so. |
| MB_SLAVE_DEVICE_BUSY | 6 | The device is busy processing data or a command. |
| MB_NEGATIVE_ACKNOWLEDGE | 7 | The request from a device has been rejected. |
| MB_MEMORY_PARITY_ERROR | 8 | A parity error occurs. The sender's data is different from the receiver's. |
| MB_ILLEGAL_PORT | 9 | The port is invalid. |
| MB_ILLEGAL_LENGTH | 10 | The data length is incorrect. |
| MB_TIMEOUT | 11 | The command has not been finished within the predefined time period. |
| MB_TRANSMIT_FAILED | 12 | The data cannot be transmitted. |
| MB_RECEIVE_FAILED | 13 | The data cannot be received. |