Mitsubishi Electronics FX3G User Manual

698

/FX

3GC

/FX

3UC

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)

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)

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

and

3UC

PLCs.)

0 (fixed)

PLC Destination Device (head address)

Applicable Devices D•R

Block Length

1 Point

8H
Diagnosis
(Available only
in FX

and

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)

Applicable Devices D•R

Block Length

Sub-function: AH
Clear Counter and
Diagnostic Register

0 (fixed)

(Slave response: echo of

)

Applicable Devices D•R

Block Length

1 Point