IDEC FT1A Series User Manual page 279

Function Code 06 (Preset Single Register)
Function code 06 changes word device data of D (data register).
Communication Frame
Request from Modbus Master
Slave No.
xxh
ACK Reply from Modbus Slave
Slave No.
xxh
NAK Reply from Modbus Slave
Slave No.
xxh
Communication Example
Write 8000 to data register D1708.
D1708 → (1708 – 0) + 400001 = 401709
Modbus address: 401709
Purpose
Extract lower 5 digits → 1709
1709 – 1 = 1708 = 6ACh
Communication frame address: 06ACh
Condition Slave No. 8
RTU Mode
•
Request from Modbus Master
ACK Reply from Modbus Slave
NAK Reply from Modbus Slave
Function Code Address
06h xxxxh
Function Code Address
06h xxxxh
Function Code Error Code
86h xxh
08 06 06AC 1F40 (CRC)
08 06 06AC 1F40 (CRC)
08 86 xx (CRC)
S AXIS P
MART
New Data
xxxxh
Acknowledge
Data
xxxxh
/L U ' M FT9Y-B1378
RO ITE SER S ANUAL
11: M C
ODBUS OMMUNICATION
11-15