Modbus TCP / Modbus UDP vacon • 91
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7
7.6.2 Example 2 - Read process data
Read the Process Data 42103…42104 with command 4 (Read Input Registers).
Command Master - Slave:
Message frame:
The reply to the Read Input Registers message contains the values of the read registers.
Answer Slave - Master:
Reply frame:
ADDRESS 01 hex Slave address 1 hex (= 1)
FUNCTION 04 hex Function 4 hex (= 4)
Starting address HI 08 hex Starting address 0836 hex (= 2102)
DATA Starting address LO 36 hex
No. of registers HI 00 hex Number of registers 0002 hex (= 2)
No. of registers LO 02 hex
ERROR CHECK CRC HI 93 hex
CRC LO A5 hex CRC 93A5 hex (= 37797)
01 04 08 36 00 02 93 A5
ADDRESS 01 hex Slave address 1 hex (= 1)
FUNCTION 04 hex Function 4 hex (= 4)
Byte count 04 hex Byte count 4 hex (= 4)
DATA Data HI 13 hex
Speed reference = 1388 hex (=5000 =>
50.00%)
Data LO 88 hex
Data HI 09 hex
Output Frequency = 09C4 hex (=2500
=>25.00Hz)
Data LO C4 hex
ERROR CHECK CRC HI 78 hex
CRC LO E9 hex CRC 78E9 hex (= 30953)
01 04 04 13 88 09 C4 78 E9