DamperAnalog

DamperAnalog (FB)

FUNCTION_BLOCK DamperAnalog

Short description

Control of a continuous damper actuator with continuous position feedback Typical application: continuous recirculation damper of an HVAC system

Representation

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
rY	REAL			Setpoint - Position
xForce	BOOL		FALSE	Forced override by manual mode
xAlarmIn	BOOL		FALSE	Actuator fault message
rU	REAL		0.0	Feedback of the damper position
eAO	HVACTYPES.eManNum	HVACTYPES.eManNum.Auto, HVACTYPES.eManNum.Man	HVACTYPES.eManBin.Auto	Operating mode of manual override - hardware
rPoti	REAL		0.0	Manual value of the manual override - hardware

Outputs

Name	Data type	Value range	Initial value	Function
rHA	REAL			Control signal to damper actuator after manual override
rAA	REAL			Control signal to damper actuator before manual override
xAlarmPos	BOOL			Fault message from position monitoring
xAlarm	BOOL			Aggregate fault
xAuto	BOOL			Collective automatic mode message

Setpoints / parameters

Name	Data type	Value range	Initial value	Function
udiControlTime	UDINT	10s … 600s	150s	Duration of the position monitoring
rControlDiff	REAL		7.0 %	maximum permissible deviation between setpoint and actual position in %
xControl	BOOL		TRUE	Enablement of the position monitoring
xForceOption	BOOL		FALSE	State of the output rHA under forced override
rManValue	REAL		0.0	Manual value
eManModeN	eMANNUM	eMANNUM.Auto, eMANNUM.Man	eMANBIN.Auto	Operating mode of the manual override

Function description

Control signal to damper actuator before manual override rAA

The control signal of the damper actuator before manual override rAA is taken unchanged from the input Setpoint - Position rY over.

Control signal to damper actuator after manual override rHA

The control signal of the damper actuator after manual override rHA corresponds to the control signal of the damper actuator before manual override rAA additionally extended by a manual override module and by a forced override.

rAA	eManModeN	xForce	xForceOption	rHA	Notes
X	eMANNUM.Auto	FALSE	X	rAA	Manual override module in automatic
X	eMANNUM.Man	FALSE	X	rManValue	Manual override module in manual operation
X	X	TRUE	FALSE	0.0	Forced override 0.0
X	X	TRUE	TRUE	100.0	Forced override 100.0

Legend: X = don't care

Position monitoring

The position monitoring can be enabled ( xControl = TRUE ) or disabled ( xControl = FALSE ). When position monitoring is enabled, the absolute value of the difference between the control signal after manual override rHA and the position feedback from the damper actuator rU is determined and compared with the threshold rControlDiff . If this difference permanently exceeds the threshold during an alarm delay udiControlTime an alarm signal is generated, provided at the same time the feedback - automatic operation eAO signals the automatic operation ( eAO = HVACTYPES.eManNum.Auto ). This alarm signal is forwarded to the output xAlarmPos transferred ( xAlarmPos = TRUE ). The alarm signal is deactivated again ( xAlarmPos = FALSE ) as soon as the difference falls below the threshold for the first time.

Aggregate fault xAlarm

The aggregate fault xAlarm is activated ( = TRUE ) if xAlarmPos or the input xAlarmIn is active. In all other cases the collective fault xAlarm is not activated ( = FALSE ).

Collective automatic mode message xAuto

The collective automatic mode message xAuto is activated ( = TRUE ) if the input eAO has the value HVACTYPES.eManNum.Auto and the setpoint / parameter eManModeN contains the value eMANNUM.Auto. In all other cases the collective message automatic operation xAuto is not activated ( = FALSE).

Forced override xForce

The forced override acts directly on the output rHA. With the parameter xForceOption it is defined which state the output rHA assumes at TRUE on the input xForce takes. When xForceOption = FALSE If the input xForce is TRUE, then the output rHA set to 0. At xForceOption = TRUE If the input xForce is TRUE, then the output rHA set to 100.

CODESYS

InOut:

Scope	Name	Type	Initial
Input	rY	REAL
Input	xForce	BOOL	FALSE
Input	xAlarmIn	BOOL	FALSE
Input	rU	REAL	0
Input	eAO	eManNum	eManNum.Auto
Input	rPoti	REAL	0
Output	rHA	REAL
Output	rAA	REAL
Output	xAlarmPos	BOOL
Output	xAlarm	BOOL
Output	xAuto	BOOL
Input Const	udiControlTime	UDINT	200
Input Const	rControlDiff	REAL	7
Input Const	xControl	BOOL	TRUE
Input Const	xForceOption	BOOL	FALSE
Input Const	rManValue	REAL	0
Input Const	eManModeN	eMANNUM	eMANNUM.Auto