Math OperationsIntermediateIEC 61131-3

MOD (Modulo)

Returns the remainder after integer division of two values.

The MOD (Modulo) function returns the remainder after integer division of the first input by the second input. MOD is useful for creating cyclic patterns, detecting even/odd values, implementing circular buffers, and distributing items across lanes. For example, MOD(Count, 4) cycles through 0, 1, 2, 3, 0, 1, 2, 3... as Count increments.

Parameters

Inputs

Name	Type	Description
IN1	ANY_INT	Dividend
IN2	ANY_INT	Divisor (must not be zero)

Outputs

Name	Type	Description
OUT	ANY_INT	Remainder (IN1 MOD IN2)

Ladder Logic Example

// Ladder Logic - MOD (Lane Distribution)
//
// |----[MOD]----|
// | IN1: Part_Count       |
// | IN2: 4                |
// | OUT: Lane_Number      |

Structured Text Example

Lane_Number := Part_Count MOD 4;
// 0, 1, 2, 3, 0, 1, 2, 3...

Is_Even := (Value MOD 2) = 0;

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Platform-Specific Implementation

Siemens (TIA Portal)

Use MOD instruction in TIA Portal SCL. In LAD/FBD, use DIV and MUL to calculate remainder.

Allen-Bradley (Studio 5000)

No native MOD; calculate using: Remainder = IN1 - (IN1/IN2)*IN2.

CODESYS

Use MOD operator in ST. Available as function block in some libraries.

Common Applications

Cyclic lane distribution
Even/odd detection
Circular buffer indexing
Periodic event triggering
Time-of-day calculations

Frequently Asked Questions

What is MOD (Modulo) in PLC programming?

Returns the remainder after integer division of two values. The MOD (Modulo) function returns the remainder after integer division of the first input by the second input. MOD is useful for creating cyclic patterns, detecting even/odd values, implementing circular buffers, and distributing items across lanes.

What are common applications of MOD (Modulo)?

MOD (Modulo) is commonly used for: Cyclic lane distribution, Even/odd detection, Circular buffer indexing, Periodic event triggering, Time-of-day calculations.

How do I use MOD (Modulo) in different PLC platforms?

Siemens: Use MOD instruction in TIA Portal SCL. In LAD/FBD, use DIV and MUL to calculate remainder. Allen-Bradley: No native MOD; calculate using: Remainder = IN1 - (IN1/IN2)*IN2. CODESYS: Use MOD operator in ST. Available as function block in some libraries.