Knowledge base
Modbus TCP errors and exception response
If a device receives a request but cannot execute it, it returns an exception response. The function code is increased by 80h and the next byte contains the error code.
| Code | Name | Meaning |
|---|---|---|
01 | Illegal Function | The device does not support the requested function. |
02 | Illegal Data Address | The register address or range is not available. |
03 | Illegal Data Value | The value or quantity is not accepted by the device. |
06 | Slave Device Busy | The device is temporarily busy. |
In FaScan, check Endpoint, Unit ID, function code, register address and raw bytes in the traffic window.
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