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11: MODBUS COMMUNICATION
Function Code 16 (Preset Multiple Registers)
Function code 16 changes word device data of D (data register). One through 64 consecutive words can be changed.
Communication Frame
Request from Modbus Master
Slave No.
Function
Code
Address
No. of
Words
Quantity of
Data
First High
Byte
First Low
Byte
Last Low
Byte
xxh
10h
xxxxh
xxxxh
xxh
xxh
xxh
xxh
ACK Reply from Modbus Slave
Slave No.
Function Code
Address
No. of Words
xxh
10h
xxxxh
xxxxh
NAK Reply from Modbus Slave
Slave No.
Function Code
Error Code
xxh
90h
xxh
Communication Example
Write the following data to four data registers D1708 through D1711.
D1708
(1234h)
Purpose
D1709
(5678h)
D1710
(ABCDh)
D1711
(EF01h)
D1708  (1708 – 0) + 400001 = 401709
Modbus address: 401709
Extract lower 5 digits  1709
1709 – 1 = 1708 = 6ACh
Communication frame address: 06ACh
Condition
Slave No. 8
 RTU Mode
Request from Modbus Master
08 10 06AC 0004 08 12 34 56 78 AB CD EF 01 (CRC)
ACK Reply from Modbus Slave
08 10 06AC 0004 (CRC)
NAK Reply from Modbus Slave
08 90 xx (CRC)
SMARTAXIS PRO/LITE USER'S MANUAL FT9Y-B1378
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