BECKHOFF BC7300 - Manual (Page 37)

BC7300 37
BC7300 Error Answers
EXCEPTION RESPONSE When the user sends the slave either a request or information that the Bus
Coupler does not understand, the BC7300 responds with an error report.
This answer contains the function and the error code. 0x80 is added to the
value returned by the function.
Code Name
Meaning
1 ILLEGAL FUNCTION Function not implemented
2 ILLEGAL DATA
ADDRESS
Invalid address or length
3 ILLEGAL DATA VALUE Invalid parameter
•
Diagnostic functions
• Incorrect number of read/write
accesses to the register
4 SLAVE DEVICE ERROR Watchdog or K-Bus error
Example The following example contains an invalid "Start address".
Query
BYTE Contents
Example
1 Slave address 0B
2 Function 01
3 Start address high 0D
4 Start address low FF
5 Data high FF
6 Data low 01
7 LRC
The slave's answer contains the function plus 0x80, together with error
code "02", i.e. an invalid address.
Response
BYTE Contents
Example
1 Slave address 0B
2 Function 81
3 Error code 02
4 LRC