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Instruction Parameters

Supported PLC Series

PLC-AESPLC-FBPLC-ES

Supported Data Registers

MXYKLFTCSZRQD@DConstant
c
v

Supported Flags

FlagBitSupport
ErrorF11.0
ZeroF11.1
CarryF11.2

Number of Steps

Steps
3

Operands

OperandDescription
cThe first operand.
Entries are only counter data registers.
vThe second operand.
Entries are unsigned WORD data registers or constants.
This is the value the counter contact, c, will energize at.

The unsigned value range is 0 ~ 65,535 (216-1).
The Hexadecimal value range is H0000 ~ HFFFF.

Signed value entries will be treated as unsigned values.

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 Z exceeds its range. The valid range of the data register Z is Z128 ~ Z1023 when using Function Block implementation. F11.0 turns ON when the value of the data register, CC, exceeds the range of 0 ~ 65,535 (unsigned).

Instruction Behavior

The CTR instruction behaves as follows:

  • The data register C assigned to c is a BOOL data register.
    • CS and CC express the detailed value of the data register C assigned to c.
      • CC is a WORD data register used for the current count value of c.
      • CS is a WORD data register used for the count setting value of c.
        • The value of CS is equal to the value of v.
  • The value of CC increases each time the instruction is energized.
    • The counter contact c turns ON when the value of CC is equal to v.
  • If the value of CC is equal to v and CC is energized again, CC will be reset to 0.
  • The counter contact assigned to c can be used as an A or B contact.
  • When the counter contact meets the RST instruction, the counter contact does NOT turn ON (1), even if the current value reaches setting value.

Ladder Diagram Examples

CTR

CTR ring-counter instruction overview showing CC incrementing from 0 to v, then resetting to 0 on the next count.

The CTR instruction starts from 0 and counts up to the value v. If it is energized one more time, the count data register, CC, will reset to 0.

Initial CTR ladder diagram with C3.0 = 0, CC3.0 = 0, and set value CS3.0 = 6.

The initial value of the BOOL counter data register, C3.0, is 0. The initial value of the WORD current count data register, CC3.0, is 0. The initial value of the WORD set count data register, CS3.0, is 6.

CTR ladder diagram after M3.0 turns ON, incrementing CC3.0 to 1.

When the contact, M3.0, is powered ON (1), the counter instruction counts up by 1, increasing the current count data register, CC3.0, to 1.

CTR ladder diagram showing count progression as CC3.0 continues incrementing from 1.
CTR ladder diagram showing CC3.0 continuing to increase.
CTR ladder diagram showing CC3.0 approaching 5.

When the contact, M3.0, is powered ON (1) again, the counter instruction counts up by 1, increasing the current count data register, CC3.0, to 5.

CTR ladder diagram showing CC3.0 = 5, one step below set value CS3.0 = 6.
When the contact, M3.0, is powered ON (1) again, the counter instruction counts up by 1, increasing the current count data register, CC3.0, to 6.

When the contact, M3.0, is powered ON (1) again, the counter instruction counts up by 1, increasing the current count data register, CC3.0, to 6.

Since CC3.0 is equal to CS3.0, the BOOL counter data register, C3.0, is set to 1.

Since CC3.0 is equal to CS3.0, the BOOL counter data register, C3.0, is set to 1. As a result, the coil, Y3.0, is energized.

When the contact, M3.0, is powered ON (1) again, the counter instruction counts up by 1, resetting the current count data register, CC3.0, to 0.

When the contact, M3.0, is powered ON (1) again, the counter instruction counts up by 1, resetting the current count data register, CC3.0, to 0.

Ladder Diagram Example for MapleLogic CTR instruction.
CTR ladder diagram after M3.0 turns ON, incrementing CC3.0 to 1.

When the contact, M3.1, is powered ON (1), the current count data register, CC3.0, is reset to 0.

Ladder Diagram Example for MapleLogic CTR instruction.
CTR ladder diagram after M3.0 turns ON, incrementing CC3.0 to 1.