Example 3 - Exception Response - Vacon optea Installation Manual

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7.6.3

Example 3 - Exception response

In an exception response, the Slave sets the most-significant bit (MSB) of the function code to 1. The
Slave returns an exception code in the data field.
Command Master - Slave:
ADDRESS
FUNCTION
DATA
ERROR CHECK
Message frame:
01 04 17
Exception response
Answer Slave - Master:
ADDRESS
FUNCTION
DATA
ERROR CHECK
Reply frame:
01 84 04
7
Starting address HI
Starting address LO
No. of registers HI
No. of registers LO
CRC HI
CRC LO
70 00 05 34
Error code
CRC HI
CRC LO
42 C3
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01 hex Slave address 1 hex (= 1)
04 hex Function 4 hex (= 4)
17 hex Starting address 1770 hex (= 6000)
70 hex
Invalid number of registers 0005 hex (=
00 hex
5)
05 hex
34 hex
66 hex CRC 3466 hex (= 13414)
55
01 hex Slave address 1 hex (= 1)
84 hex Most significant bit set to 1
04 hex Error code 04 => Slave device failure
42 hex
C3 hex CRC 42C3 hex (= 17091)
Modbus TCP / Modbus UDP