Micromod MOD: Modcell 2050R MODBUS Communications - Manual (Page 42)

IB-23C650M
MODBUS PROTOCOL
Preset Multiple Registers
Master Message Format Bytes
0 1 2 & 3 4 & 5 6 7 & 8 ...
x &
x+1
x +2
& x+3
Device
Address Function
Code Starting
Register
Number Number
of
Registers Number
of Data
Bytes Register
Data 1 ... Register
Data n
CRC
Slave Response Bytes
0 1 2 & 3 4 & 5 6 & 7
Device Address Function Code Starting Register Number Number of Registers CRC
Coil Data Example
Coil data is packed 1 bit per coil. The low order bit of the first data byte
contains the addressed coil and unused bits are zero filled. For instance, if
coils 22 through 33 are requested, two data bytes will be returned with the coil
data located as follows; (coils 22,24,25,26,29,30,32 and 33 are on).
coil # 29 26 25 24 22 33 32 30
data bytes 1 & 2 1 0 0 1 1 1 0 1 0 0 0 0 1 1 0 1
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