CoolOutProtection

CoolOutProtection (FB)

FUNCTION_BLOCK CoolOutProtection

Short description

Activation of a cool-out protection mode with adjustable minimum runtime (controlled variable: room temperature) Typical application: activation of the cool-out protection mode during idle operation of a ventilation system

Representation

Function description

General

This function block controls the activation of the cool-out protection mode ( xEn = TRUE ) with an adjustable minimum runtime udiMinTime by comparing the room temperature rRoomTemp with the threshold for the cool-out protection mode rSetPtTempCoolOut. The minimum runtime is always activated if the room temperature rRoomTemp falls below the threshold rSetPtTempCoolOut by at least 0.4K. At the output tOffDelay* the already elapsed minimum runtime is shown during the minimum runtime in the range 0 - udiMinTime displayed.

Enable / disable of the cool-out protection mode xEn

xReqAHU	rRoomTemp	Minimum runtime active	xEn	Notes
TRUE	X	X	FALSE	Cool-out protection mode disabled by ventilation system
FALSE	> rSetPtTempCoolOut + 0.4	FALSE	FALSE	Cool-out protection mode disabled by room temperature
FALSE	< rSetPtTempCoolOut - 0.4	FALSE	TRUE	Cool-out protection mode enabled by room temperature
FALSE	X	TRUE	TRUE	Cool-out protection mode enabled by minimum runtime
FALSE	< rSetPtTempCoolOut - 0.4	TRUE	TRUE	Cool-out protection mode enabled by room temperature and minimum runtime

Legend: X = don't care

CODESYS

InOut:

Scope	Name	Type	Initial
Input	rSetPtTempCoolOut	REAL
Input	rRoomTemp	REAL
Input	xReqAHU	BOOL
Output	xEn	BOOL
Output	tOffDelay	TIME
Input Const	eMinTimeBase	eTime	eTime.Minute
Input Const	udiMinTime	UDINT	30