Mitsubishi MELSEC FX3U Series User Manual (English)

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4 Conversion of the Projects

4.2 Precautions when Converting the Projects

Correction of structured ladder/FBD program

• The method of thinking for execution order is different for the GX Works2 structured ladder/FBD and GX Works3 FBD/LD

language. Display the execution order and check the contents.

• The operation of the return element is different for the GX Works2 structured ladder/FBD and GX Works3 FBD/LD

language. For details of the return element of GX Works3, refer to the following.

GX Works3 Operating Manual

• For the GX Works2 structured ladder/FBD and GX Works3 FBD/LD language, there are different cases in the input/output

parameter numbers of the function parts/function block parts and the order. In this case, it will be displayed as an undefined

FB/FUN. Select [Edit]→[FB/FUN update] to update the definition information, and correct the program.

• When the program is made to refer to a standard FB member in the GX Works2 structured ladder/FBD, a conversion error

may occur after opening with GX Works3. In this case, check the member name and class of the standard FB, and correct

the program.

• For the GX Works3 FBD/LD language, the input/output parameter of the function parts/function block elements can only be

inverted. When elements other than the above are inverted for GX Works2 structured ladder/FBD, the connecting line of

that element will be deleted. Correct the program so that the operation will be equal to GX Works2 structured ladder/FBD.

• For the GX Works3 FBD/LD language, the wired OR of the FBD elements are not supported. Correct the program so that

the operation will be equal to GX Works2 structured ladder/FBD, or a conversion error will occur.

• When using the pointer branch instructions (CJ), jump, and sub routine program, a conversion error may occur. For details,

refer to the following.

MELSEC iQ-F FX5 Programming Manual (Program Design)

• According to the difference of the GX Works2 structured ladder/FBD editor and GX Works3 FBD/LD editor, the layout of the

program may change. Correct the layout appropriately.

• Ladder block label used in the GX Works2 structured ladder/FBD will be defined as a pointer type in local label.

• For GX Works3 FBD/LD language, the timer and counter device cannot reset by coil. Use the RST instruction.

• When the output of a function that executes on a pulse is connected to the input of another function, an error occurs.

Receive the output by a device or label and then connect to the input.

Instructions Requiring Special Action When Replacing Instructions of ST programs

The following instructions require settings after the project conversion.

FX3 Series → MELSEC iQ-F Action content

DHSCS_I → DHSCS_I When an out of range “I” device is specified as the fourth

parameter, it will be replaced with OUT instructions.

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Mitsubishi MELSEC FX3U Series Specifications

General

Series	MELSEC FX3U
Program Memory	64k steps
Type	PLC (Programmable Logic Controller)
I/O Capacity	Up to 384 points (with expansion)
Programming Language	Function Block Diagram
Communication Protocols	RS-422, RS-485
Power Supply	24 VDC or 100-240 VAC
Execution Speed	0.065 μs per basic instruction
Built-in Functions	PID control
Built-in Communication Ports	RS-422
Expansion Modules	communication modules
High-speed Counters	Up to 6 channels, up to 100 kHz
Pulse Output	Up to 100 kHz
Operating Temperature	0°C to 55°C