25
7. Modbus TCP
Dual port ethernet option board installation manual
MN032004EN October 2017 www.eaton.com
Reply framee:
01
04
04
13
88
09
C4
78
E9
7.2.3 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 – Slavee:
Address
01 hex Slave address 1 hex (= 1)
Function
04 hex Function 4 hex (= 4)
Data
Starting address HI
17 hex Starting address 1770 hex (= 6000)
Starting address LO 70 hex
No. of registers HI
00 hex Invalid number of registers 0005
hex (=5)
No. of registers LO
05 hex
Error
check
CRC HI
34 hex
CRC LO
66 hex CRC 3466 hex (= 13414)
Message framee:
01
04
17
70
00
05
34
55
Exception response
Answer slave – Mastere:
Address
01 hex
Slave address 1 hex (= 1)
Function
84 hex
Most significant bit set to 1
Data
Error code
04 hex
Error code 04 => Slave device failure
Error
check
CRC HI
42 hex
CRC LO
C3 hex
CRC 42C3 hex (= 17091)
Reply framee:
01
84
04
42
C3