SUB block
Short summary
Name |
SUB |
→POU type |
|
Category |
|
Conform to →IEC-standard |
currently restricted
|
Graphical interface |
|
Available since |
|
Functionality
The mathematical function subtraction is called: The block returns the difference for IN1 – IN2 .
No check of invalid connections
For some blocks, invalid connections are not checked by logi.CAD 3. Therefore, enter code in your application to detect invalid connections (e.g. IF-statements). See "Examples for invalid Connections".
See "IEC-blocks for the application" for information what the consequences of an invalid connection might be.
Inputs, return value
|
Identifier |
Description |
|
Inputs: |
IN1 |
REAL, LREAL, USINT, UINT, UDINT, ULINT, SINT, INT, DINT, LINT oder TIME |
1st value |
IN2 |
REAL, LREAL, USINT, UINT, UDINT, ULINT, SINT, INT, DINT, LINT oder TIME |
2nd value |
|
Return value: |
– |
REAL, LREAL, USINT, UINT, UDINT, ULINT, SINT, INT, DINT, LINT oder TIME |
|
Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.
Example for usage within ST-editor
PROGRAM Test
VAR
result : REAL;
END_VAR
result := SUB(IN1 :=
4.0
, IN2 :=
3.0
); (* The variable
'result'
evaluates to
'1.0'
. *)
END_PROGRAM
When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.
Examples for invalid connections
An invalid connection due to →overflows or →underflows might occur during a calculation using SUB.
SUB(IN1 := SINT#100, IN2 := SINT#-50);
(* Overflow: '100 - -50' would evaluate to '150' but calculates '-106'. Upper limit for SINT is '127'. *)
SUB(IN1 := SINT#-100, IN2 := SINT#50);
(* Negative overflow: '-100 - 50' would evaluate to '-150' but calculates '106'. Lower limit for SINT is '-128'. *)