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6
Chapter
Reading Data
Reading Read-Only Bit Data (Function Code: 02H)
The unit reads bit data continuously for the specified number of bits from the first number to start reading from.
The slaves systematically send the read data in 8-bit units.
Message Composition
Caution
When the number of bits to be read is not a multiple of eight, unrelated bits (on the MSB side) all become "0".
Function Code 02H
Max. No. of Bits to Read in One Message 8 bits
Relative Address 0000H to 000CH
Coil Number 10001H to 10013H
Master Slave
Command Message (bytes)
Station No.
Function Code
Number to Start Reading
(Relative Address)
Upper number
Lower number
No. of Bits to Read
00H
Lower number
CRC Data
Upper number
Lower number
Reply Message Composition (bytes)
Station No.
Function Code
No. of Bytes to Read (01H)
State of first 8 bits
CRC Data
Upper number
Lower number
■
Bit Data to Read List
MSB LSB
State of first 1 bit
State of last 1 bit
00000000
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