Burner2Stage

Burner2Stage (FB)

FUNCTION_BLOCK Burner2Stage

Short description

Control of a heat generator (temperature control via binary control commands More / Less) Typical application: heat generation

Representation

Function description

General

This function block is used to control / regulate a heat generator depending on the demand of the heat generator xEn, the supply setpoint temperature rSetPtTemp and the supply temperature rFdT. The enable / disable of the heat generator is done via the output xHB (FALSE = lockout, TRUE = enable). The flow temperature control (analogously also boiler temperature control) is carried out by means of two power controllers (P-controllers, slow and fast) via the outputs xMoreHB and xLessHB. The enabling of the control is delayed (setpoint / parameter udiWaitControl) after the running feedback (xFb = TRUE) of the heat generator. The following function blocks are essentially used:

ControlP

Out3P

OperatingHours

ManBin

Enable / disable of the heat generator

The enabling of the heat generator (xAB = TRUE, xHB = TRUE (eManModeB = eManBin.Auto)) occurs if the supply temperature rFdT the sum of supply setpoint temperature rSetPtTemp and setpoint / parameter rSwitchOnPoint falls below, at the same time the general enable xEn active (= TRUE) and the minimum off-time is not active. The disabling of the heat generator (xAB = FALSE, xHB = FALSE (eManModeB = eManBin.Auto)) occurs if the supply temperature rFdT the sum of supply setpoint temperature rSetPtTemp and setpoint / parameter rSwitchOffPoint exceeds and at the same time the general enable xEn is active (= TRUE). Between two consecutive operating cycles a minimum off-time is always inserted (duration = udiTimeMinOff, display - remaining time: tOnDelay). The minimum off-time begins with the falling edge (TRUE > FALSE) at the input xFb.

Temperature control of the heat generator

The enabling of the temperature control is delayed (duration = udiWaitControl, display - remaining time: tOnControlDelay) after the active running signal (xFb = TRUE) of the heat generator. The disabling of the temperature control occurs immediately after the inactive running signal (xFb = FALSE) of the heat generator (switch-off value: rYDisabled). The two internal power controllers (P-controllers, slow and fast, output range each -100.0 - 100.0 %) are enabled/disabled simultaneously. (Setpoint = desired flow temperature rSetPtTemp, actual value = supply temperature rFdT). The control signals of both power controllers are fed through a minimum-value selection (forwarding the signal with the smaller value) to the output controller in the range -100.0 - 100.0 %. The output controller finally generates output signals for a 3-point actuator (pulse width modulation, integration interval = tIntegration) with the outputs xMoreHB or xLessHB. The constant pulse duration for the two outputs is freely adjustable in each case (tImpulsOpen or tImpuls Close), the variable pulse pauses are determined by the output controller. The two power controllers can be configured individually and independently of each other (P-controller fast: gain factor rKpBig, P-controller slow: gain factor rKpTiny).

Manual override of the digital outputs

All digital control outputs after manual override (xHB, xMoreHB*, xLessHB) can either be operated in automatic mode (eMANBIN.Auto) or in one of the two manual operating modes (eMANBIN.ManOn, eMANBIN.ManOff).

xAB	eMANBIN	xHB	Notes
FALSE	eMANBIN.Auto	FALSE	Manual override module in automatic
TRUE	eMANBIN.Auto	TRUE	Manual override module in automatic
X	eMANBIN.ManOn	TRUE	Manual override module in manual operation On
X	eMANBIN.ManOff	FALSE	Manual override module in manual operation Off

Legend: X = any

Aggregate fault xAlarm

The aggregate fault xAlarm is active (= TRUE) if the fault signal of the heat generator xAlarmIn is active (= TRUE). In all other situations the aggregate fault xAlarm not active (= FALSE).

Collective automatic-mode message xAuto

The collective automatic-mode message xAuto is activated (= TRUE) if the following conditions are met simultaneously:

• Input eAOO = HVACTYPES.eManBin.Auto

• Input eAOOMore = HVACTYPES.eManBin.Auto

• Input eAOOLess = HVACTYPES.eManBin.Auto

• Setpoint / parameters eManModeB = eMANBIN.Auto

• Setpoint / parameters eManModeBMore = eMANBIN.Auto

• Setpoint / parameters eManModeBLess = eMANBIN.Auto

Operating hours counter - heat generator

The operating hours counter (udiOperatingHours, udiCountFb) for the heat generator is active when the running signal is active (xFb = TRUE).

Write access to the counter values

Via the path 'InstanceName._OperatingHours.udiOperatingHours' or 'InstanceName._OperatingHours.udiCountFb' write access to both counters is possible.

Prerequisite for the use of the function block Burner3P

The use of the TimeRead2 function block is required for correct operation.

Current calculated power of the heat generator rPos

The current calculated power of the heat generator is displayed at the output rPos in the range 0.0 - 100.0 %. For this, the correct specification of the travel time of the actuator between minimum and maximum power (tDuration) is required. No repositioning to a reference position takes place.

Feedback of the heat generator power rU

The current actual Power of the heat generator can be connected at the input rU . This input is currently not used for control and regulation purposes.

Not active state (xEn = FALSE)

xHB	xAB	xMoreHB	xMoreAB	xLessHB	xLessAB	rPos	tOnDelay	tOnControlDelay	dtLastFb	udiOperatingHours	udiCountFb	xAlarm	xAuto	Notes
FALSE (eManModeB = eManBin.Auto)	FALSE	FALSE (eManModeBMore = eManBin.Auto)	FALSE	FALSE (eManModeBLess = eManBin.Auto)	FALSE	0.0 %	old value	old value	old value	old value	old value	State of xAlarmIn	old value	xEn = FALSE

Legend: X = any

CODESYS

InOut:

Scope	Name	Type	Initial
Input	xEn	BOOL
Input	rSetPtTemp	REAL
Input	xFb1	BOOL
Input	xFb2	BOOL
Input	xAlarmIn	BOOL
Input	eAOO1	eManBin	eManBin.Auto
Input	eAOO2	eManBin	eManBin.Auto
Input	rFdT	REAL
Output	xHB1	BOOL
Output	xAB1	BOOL
Output	xHB2	BOOL
Output	xAB2	BOOL
Output	tOnDelay	TIME
Output	tOn2Delay	TIME
Output	dtLastFb	DT
Output	udiOperatingHours	UDINT
Output	udiCountFb	UDINT
Output	dtLastFb2	DT
Output	udiOperatingHours2	UDINT
Output	udiCountFb2	UDINT
Output	xAlarm	BOOL
Output	xAuto	BOOL
Input Const	udiTimeTOFxFb	UDINT	7
Input Const	udiWait2	UDINT	3
Input Const	rSwitchOffPoint1	REAL	2.5
Input Const	rSwitchOffPoint2	REAL	-1
Input Const	rSwitchOnPoint1	REAL	-2.5
Input Const	rSwitchOnPoint2	REAL	-1.5
Input Const	udiTimeMinOff	UDINT	3
Input Const	eManModeB2	eMANBIN	eMANBIN.Auto
Input Const	eManModeB1	eMANBIN	eMANBIN.Auto