KROHNE MFC 010 C Converter - Manual (Page 24)

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MFC010 Interface Manual
5.6 Error Messages in Modbus
When t he M FC010 det ects an error i n t he r equest r eceived i n a pr operly f ormatted t elegram, i t w ill
respond with an error message. The error message response telegram is formatted as follows.
Address Function Error Code CRC CRC
The most significant bit of the requested function code is set (add 128, 80
16
) in the response telegram to
indicate that an error has been detected. For example, if an error were detected in a Function 1 request,
then the returned function code would be 81
16
(129).
The single data character in the response telegram will indicate the type of error detected. These are as
follows.
1 Illegal Function The requested function code is not supported by
the MFC010 or is not valid due to the current
settings of the device.
2 Illegal Data Address The Register requested is not valid.
3 Illegal Data Value The requested data (in Write operations only) is
invalid for the register being written.
6 Slave Device Busy The MFC010 is unable to process the requested
command because an EEPROM save is in progress.
Errors due t o c ommunications f aults ( CRC er rors, P arity er rors et c) ar e logged but no response is
returned because the data in the received telegram is deemed unreliable. T he Master system can read
the error logs by using the diagnostic command (Function 08, see Section 6.8).