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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
30 External Device Communication – FNC270 to FNC276
30.7 FNC276 - MODBUS Read/Write Instruction
30.7.1 Command Code and Command Parameters
The following table shows the required command parameters for each command code.
/
1H
Read Coils
MODBUS Address:
0000H~FFFFH
Device Count:1~2000
PLC Destination Device (head address)
Applicable Devices D•R•M•Y•S
Block Length
(+ 15)
÷16
*1
2H
Read Discrete
Inputs
MODBUS Address:
0000H~FFFFH
Device Count:1~2000
PLC Destination Device (head address)
Applicable Devices D•R•M•Y•S
Block Length
(+ 15)
÷16
*1
3H
Read Holding
Register
MODBUS Address:
0000H~FFFFH
Device Count:1~125
PLC Destination Device (head address)
Applicable Devices D•R
Block Length
4H
Read Input
Register
MODBUS Address:
0000H~FFFFH
Device Count:1~125
PLC Destination Device (head address)
Applicable Devices D•R
Block Length
5H
Write Single Coil
MODBUS Address:
0000H~FFFFH
0 (fixed)
PLC Source Device (head address)
Applicable Devices
D•R•K•H•M•X•Y•S
(D•R•M•X•Y•S can be
indexed.)
Block Length 1 Point
6H
Write Single
Register
MODBUS Address:
0000H~FFFFH
0 (fixed)
PLC Source Device (head address)
Applicable Devices
D•R•K•H
(D•R can be indexed.)
Block Length 1 Point
7H
Read Exception
State
(Available only
in FX
3U and
FX
3UC PLCs.)
0 (fixed) 0 (fixed)
PLC Destination Device (head address)
Applicable Devices D•R
Block Length 1 Point
8H
Diagnosis
(Available only
in FX
3U and
FX
3UC PLCs.)
Sub-function: 0H
Loop-back Test
Sub-function Data
(loop-back data):0~65535
Loop-back Test Data
(Slave response: echo of )
Applicable Devices D•R
Block Length 1 Point
Sub-function: 1H
Restart
Communication
Sub-function Data:
0x0000: Do Not Reset
Event Log
0xFF00: Reset Event Log
(Slave response: echo of )
Applicable Devices D•R
Block Length 1 Point
Sub-function: 2H
Return
Diagnostic Register
0 (fixed)
PLC Destination Device (head address)
Applicable Devices D•R
Block Length 1 Point
Sub-function: 3H
Change ASCII Input
Delimiter
Sub-function Data (ASCII
Mode End of Message
Character): 00H~FFH
(Slave response: echo of )
Applicable Devices D•R
Block Length 1 Point
Sub-function: 4H
Force Listen Only
Mode
0 (fixed)
0 (fixed)
Applicable Devices D•R
Block Length 0
Sub-function: AH
Clear Counter and
Diagnostic Register
0 (fixed)
(Slave response: echo of )
Applicable Devices D•R
Block Length 1 Point
S
1
S
2
S
3
S
4
D
S
3
S
3
S
3
S
3
S
3
S
3
S
3
S
3