Mitsubishi Electric MELSEC iQ-RJ71C24-R4 - Read Input Registers (FC: 04 H)

3 MODBUS STANDARD FUNCTION DETAILS
3.4 Read Input Registers (FC: 04H)
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3.4 Read Input Registers (FC: 04H)
Operation description
Reads one or multiple input register values.
Request message format (from master to slave)
Response message format (from slave to master)
■ When completed successfully
■ When completed with an error
• For example, when n = 4, the number of read bytes is 4  2 = 8.
(H) (L) (H) (L)
04H
Data
Number of read pointsStart input register number
specification
Function code
(0000H to FFFFH) (0001H to 007DH)
04H
(H) (L) (H) (L)
DataFunction code
Number of read
bytes n×2
Device data 1 Device data n
Number of read bytes n×2
84H
Data
Exception code
Function code