Hardware manual

12 Modbus
2-251
Chap.2
FC4 Read input registers
Reading of Input Register (IR) consecutively
(Request)
Byte 7 FC (Function code)=04
Byte 8-9 Reference No.
Byte 10-11 Number of read words (1 to 125 words)
(Normal response)
Byte 7 FC (Function code)=04
Byte 8 Number of bytes for the response (number of read words x 2)
From Byte 9 Read data
(Abnormal response)
Byte 7 FC (Function code)=84 (HEX)
Byte 8 Exception code 01 or 02
(Example)
Reading of IR300001 (1 word). The read value is 1234 (HEX).
04 00 00 00 01 => 04 02 12 34