Modbus Instruction manual 05/0842
42
Modbus Instruction manual 05/08
8.1.5 Function Code 8, Diagnostics
Example 1a:
Clearing all Diagnostic Counters (Sub function 0x0A) in the frequency inverter with
address 1.
Request: Master Î Frequency Inverter
Field: Adr Funct. Sub function Data CRC
Hex
01 08 00 0A 00 00 C0 09
Response: Frequency Inverter Î Master
Field: Adr Funct. Sub function Data CRC
Hex
01 08 00 0A 00 00 C0 09
The response is an echo of the request. All counters are now set to zero.
Example 1b:
With all counters set to zero, read Diagnostic Counter 4, "Slave Message Count" (Sub
function 0x0E) from the frequency inverter with address 1.
Request: Master Î Frequency Inverter
Field: Adr Funct. Sub function Data CRC
Hex
01 08 00 0E 00 00 81 C8
Response: Frequency Inverter Î Master
Field: Adr Funct. Sub function Data CRC
Hex
01 08 00 0E 00 01 40 08
The counter value is 1(as this is the 1st message received after setting all counters
to zero).
Example 2:
Reading unknown Diagnostic Counter 8 (Sub function 0x13) from the frequency in-
verter with address 1
Request: Master Î Frequency Inverter
Field: Adr Funct. Sub function Data CRC
Hex
01 08 00 13 00 00 11 CE
Error Response: Frequency Inverter Î Master
Field: Adr Funct. Except. CRC
Hex
01 88 01 87 C0
The exception code sent is hexadecimal value 0x01 = ILLEGAL FUNCTION.
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