SEMA block

Short summary

Name	`SEMA`
→POU type	→function block
Category	IEC-block, BistableEnh
Conform to →IEC-standard	not defined in IEC-standard
Graphical interface
Available since	version 1.27.0 (for Neuron Power Engineer)

Functionality

The block represents a semaphore.

If input CLAIM is →turned on, output BUSY returns value TRUE (or an equivalent) starting with the next executed cycle. If input RELEASE is turned on, output BUSY returns value FALSE (or an equivalent).

In-/outputs

	Identifier	→Data type	Description
Inputs:	`CLAIM`	`BOOL`	set (dominant)
Inputs:	`RELEASE`	`BOOL`	reset
Outputs:	`BUSY`	`BOOL`

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

PROGRAM Test

VAR

      mySEMA   : SEMA;

      TriggerC : BOOL;

      TriggerR : BOOL;

      Out      : BOOL;

   END_VAR

   mySEMA(CLAIM := TriggerC, RELEASE := TriggerR, BUSY => Out);

   (* Instance of block 'SEMA' is called. *)

   (* Input 'CLAIM' gets value from 'TriggerC' variable. Input 'RELEASE' gets value from 'TriggerR' variable.*)

   (* Output 'BUSY' returns TRUE, if 'TriggerC' is TRUE. Output 'BUSY' returns FALSE, if 'TriggerR' is TRUE and 'TriggerC' is FALSE. *)

   (* Variable 'Out' accesses the output 'BUSY'. *)

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.