MAX_HOLD block

Short summary

Name	`MAX_HOLD`
→POU type	→function block
Category	IEC-block, SelectEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.43.0 (for Neuron Power Engineer)

Functionality

The block is a peak detector which sets the output OUT to the maximum value assigned to the input IN. Setting the input R to the value TRUE (or an equivalent) resets the output value OUT to the current input value IN.

Restrictions

The following restrictions apply to the usage of overloadable function block instances:

The declaration is limited to local variables.
The usage as array base type is not allowed.
The usage as structure element is not allowed.
Instance data cannot be displayed in the Values of Variables view.

In-/outputs

	Identifier	→Data type	Description
Inputs:	`IN`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT` or `LINT` (corresponds to →generic data type `ANY_NUM`)	input value
Inputs:	`R`	`BOOL`	reset
Outputs:	`OUT`	`REAL`, `LREAL`, `USINT`, `UINT`, `UDINT`, `ULINT`, `SINT`, `INT`, `DINT` or `LINT` (corresponds to →generic data type `ANY_NUM`)	maximum value

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic.

Example for usage within ST-editor

FUNCTION_BLOCK ExampleMaxHold

VAR

        iMaxHold : MAX_HOLD;

        inputValues : ARRAY[1..3] OF INT := [1,10,5];

        resultValues : ARRAY[1..3] OF INT;

        index : INT;

    END_VAR

    iMaxHold(IN:=0, R:=TRUE);    // Reset 'OUT' to '0'.

    FOR index := 1 TO 3 DO

        iMaxHold(IN:=inputValues[index], R := FALSE, OUT => resultValues[index]);

    END_FOR;

    // 'resultValues' evaluates to '[1,10,10]'.

    ENO := AND (resultValues[1] = 1, resultValues[2] = 10, resultValues[3] = 10);

END_FUNCTION_BLOCK

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.