Loop Begin (FOR)

Instruction Parameters

Supported PLC Series

XPnA/1R	XPnB	XPnE	XPnF	CP3A/B/P/U CP4A~D/U	CPnE	CPnF	BP	PLC-S
✓	✓	✓	✓	✓	✓	✓	✓	✓

Supported Data Registers

	M	X	Y	K	L	F	T	C	S	Z	R	Q	D	@D	Constant
n	✓	✓	✓	✓	✓	-	✓	✓	-	✓	✓	✓	✓	✓	✓

Supported Flags

Flag	Bit	Support
Error	F11.0	✓
Zero	F11.1	-
Carry	F11.2	-

Number of Steps

Steps
1

Operands

Operand	Description
n	The only operand. Entries are WORD data registers or constants. This is the number of times to repeat the instructions inside the loop statement. The value range is 1 ~ 32,767 (215-1).

Notice

Error Flag (F11.0) Notice

The error flag, F11.0, will be ON for one scan when the address of the data register assigned by @D exceeds the range of the data register, D. The range of the data register, D, is dependent on the CPU type.

• Compile errors occur under the following conditions:
  • When the value of n exceeds the range 1 ~ 32,767 (2¹⁵-1).
  • When the FOR ~ NEXT instructions are not used as a pair.
  • When the FOR ~ NEXT instructions exceed 16 levels.

Instruction Behavior

The FOR instruction behaves as follows:

• Instructions within the bounds of the FOR ~ NEXT instruction are executed n times.
  • When the loop ends, the instruction after the NEXT instruction is executed.
• Nesting FOR ~ NEXT instructions is possible up to 16 nests.
• The FOR ~ NEXT instructions must be used in pairs.

Excessive Use

If the FOR ~ NEXT instructions are used excessively, the scan time increases.
The system might be overloaded causing the CPU to shut down or initialize.

Examples

• Ladder Diagram