RS232 - Interface
BC8050 und BC815070 Version: 3.0.0
6.1.1.5.5 Function 8: Diagnosis
The diagnosis function provides a series of tests for checking the communication system between the
master and the slave and for examining a variety of internal error states within the slave. A broadcast
telegram is not supported.
The function in the query uses a subfunction code field of two bytes to define the type of test to be carried
out. The slave outputs the function code and the subfunction code in a response.
The diagnostics queries use a two-byte data field to send diagnostics data or control information to the slave.
Query
Byte Name Modbus RTU Modbus ASCII
Start - frame - - ":" 0x3A
Address 11 0x0B "0B" 0x30, 0x42
Function code 8 0x08 "08" 0x30, 0x38
Subfunction high 0 0x00 "00" 0x30, 0x30
Subfunction low 0 0x00 "00" 0x30, 0x30
Data high 2 0x02 "02" 0x30, 0x32
Data low 3 0x03 "03" 0x30, 0x33
Error check, LRC/
CRC
0xA1, 0xC0 "E8" 0x45, 0x38
End - frame t1-t2-t3 CRLF 0x0D, 0x0A
Response
Byte Name Modbus RTU Modbus ASCII
Start - frame - - ":" 0x3A
Address 11 0x0B "0B" 0x30, 0x42
Function code 8 0x08 "08" 0x30, 0x38
Subfunction high 0 0x00 "00" 0x30, 0x30
Subfunction low 0 0x00 "00" 0x30, 0x30
Data high 2 0x02 "02" 0x30, 0x32
Data low 3 0x03 "03" 0x30, 0x33
Error check, LRC/
CRC
0xA1, 0xC0 "E8" 0x45, 0x38
End - frame t1-t2-t3 CRLF 0x0D, 0x0A
Mirroring a request (subfunction 0)
Subfunction 0 causes the data that is sent to the slave by the master to be returned.
Coupler Reset (Subfunction 1)
The Bus Coupler/Fieldbus Box is reinitialized with subfunction 1, error counters are reset, and the Bus
Coupler/Fieldbus Box carries out a self-test. During the time, in which the Bus Coupler/Fieldbus Box is reset,
no telegrams are received or sent.
Note
Response with subfunction 1
Before the Bus Terminal Controller restarts, it sends a response with subfunction 1.
Note
Subfunctions 0 and 1
The BC8150 has subfunctions 0 and 1 implemented. All other subfunctions return "0".
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