User Manual of EM730 Series Inverter return (crcH } 11.3.7 Exception response normal response. Query of the master station may result in one of the following four events: When the master station sends a request to the slave station, the master station expects a If a request without communication error is received from the slave station and can be processed properly, a normal response will be returned by the slave station. If the slave station does not receive a request due to communication errors, no message will be returned. This will be regarded as a timeout by the slave station.
If the slave station receives a request but detects a communication error (parity, address, frame error, etc.), no response will be returned. This will be regarded as a timeout by the slave station. If the slave station receives a request without communication error but cannot process the request (e.g. a request to read the non-existent register), the slave station will return an exception response and the master station will be informed of the actual error. response: The exception response message has two fields different from those of the normal Function code field:
In the normal response, the slave station copies the function code of the original request in the corresponding function code field. The MSB values of all function codes are 0. In the exception response, the MSB of the function code is set to 1 by the slave station. That is, the exception response function code = normal response function code + 0x80 . Data field: The slave station can return the data from the data field in the normal response and exception code in the exception response. For the defined exception codes, Table 4-33 Definitions of Exception CodesTable 4-33.
Table 4- 33 Definitions of Exception Codes 389 Exception code Item Meaning 01H Illegal function The function code received by the slave station (inverter) is beyond the configured range (see 11.3.3Function code). 02H Illegal data The data address received by the slave station (inverter) is not