SUB¶

Returns the difference of two inputs.

Signature¶

     ┌─────────┐
IN1 ─┤         │
     │   SUB   ├─ OUT
IN2 ─┤         │
     └─────────┘

FUNCTION SUB : ANY_NUM
  VAR_INPUT
    IN1 : ANY_NUM;
    IN2 : ANY_NUM;
  END_VAR
END_FUNCTION

The return type matches the input type. SUB accepts SINT, INT, DINT, LINT, USINT, UINT, UDINT, ULINT, REAL, LREAL. Inputs of different numeric types widen to the wider one, which is also the return type; see Type Conversions. The time and date types are covered by the overloads below.

Inputs

Name	Type	Description
`IN1`	`ANY_NUM`	The minuend.
`IN2`	`ANY_NUM`	The subtrahend.

Outputs

Name	Type	Description
Return value	`ANY_NUM`	IN1 minus IN2. Same type as the inputs.

Description¶

Returns IN1 minus IN2. SUB(a, b) is the functional form of the - operator: a - b. Both forms are equivalent.

For integer types, underflow behavior wraps around (modular arithmetic).

Time and date overloads¶

SUB and the - operator are also defined on the following time and date operands (IEC 61131-3 Table 30). Each combination is the typed function in the last column and computes what it computes.

IN1	IN2	Return value	Same as
`TIME`	`TIME`	`TIME`	SUB_TIME
`DATE`	`DATE`	`TIME`	SUB_DATE_DATE
`TIME_OF_DAY`	`TIME`	`TIME_OF_DAY`	SUB_TOD_TIME
`TIME_OF_DAY`	`TIME_OF_DAY`	`TIME`	SUB_TOD_TOD
`DATE_AND_TIME`	`TIME`	`DATE_AND_TIME`	SUB_DT_TIME
`DATE_AND_TIME`	`DATE_AND_TIME`	`TIME`	SUB_DT_DT

d1 - d2 on two DATE values is therefore a TIME, not a DATE.

Each typed function has a long form over LTIME, LDATE, LTIME_OF_DAY and LDATE_AND_TIME (SUB_LTIME, SUB_LDATE_LDATE, SUB_LTOD_LTIME, SUB_LTOD_LTOD, SUB_LDT_LTIME, SUB_LDT_LDT), which applies when either operand is of a long type.

Any other combination of types is an error (P4049).

Example¶

Try it

Source

result := SUB(30, 10);   (* result = 20 *)
result := 30 - 10;       (* result = 20, operator form *)

SUB¶

Signature¶

Description¶

Time and date overloads¶

Example¶

See Also¶

References¶