Read Discrete Inputs (Fc: 02H) - Mitsubishi Electric MELSEC iQ-R Series Reference Manual

3.2

Read Discrete Inputs (FC: 02H)

Operation description
Reads the status (ON/OFF) of one or multiple inputs.
Request message format (from master to slave)
Function code
Start input number specification
02H (0000H to FFFFH)
(H)
Response message format (from slave to master)
■ When completed successfully
Function code
Number of read
bytes n
02H
• Device data 1 to n
b7 b6
Device data 1
Device data n
• The read input status is stored in the order of lower bit to higher bit.
• If the number of read points is not a multiple of eight, the remaining bits are all set to 0.
■ When completed with an error
Function code Data
Exception code
82H
Data
Number of read points
(0001H to 07D0H)
(L) (H)
Data
Device data 1 Device data n
Number of read bytes n
b5 b4 b3 b2 b1
(L)
b0
Bit device storage order
0: OFF
1: ON
3 MODBUS STANDARD FUNCTION DETAILS
3.2 Read Discrete Inputs (FC: 02H)
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