Redundance4

Redundance4 (FB)

FUNCTION_BLOCK Redundance4

Short description

Redundant control of 0 - 4 identical devices Influencing factors: demands, operating hours, operating and fault states Typical application: determination of leader and follower devices

Interfaces

Inputs

Name	Data type	Value range	Initial value	Function
wActiveNumberOfDevices	WORD		0	Number of active devices ( 0 - 4 )
xFb1	BOOL		FALSE	Running - device 1 ( TRUE = running )
xFb2	BOOL		FALSE	Running - device 2 ( TRUE = running )
xFb3	BOOL		FALSE	Running - device 3 ( TRUE = running )
xFb4	BOOL		FALSE	Running - device 4 ( TRUE = running )
xAlarm1	BOOL		TRUE	Fault - device 1 ( TRUE = fault )
xAlarm2	BOOL		TRUE	Fault - device 2 ( TRUE = fault )
xAlarm3	BOOL		TRUE	Fault - device 3 ( TRUE = fault )
xAlarm3	BOOL		TRUE	Fault - device 4 ( TRUE = fault )
uiOperatingHours1	UDINT		0	Operating hours - device 1
uiOperatingHours2	UDINT		0	Operating hours - device 2
uiOperatingHours3	UDINT		0	Operating hours - device 3
uiOperatingHours4	UDINT		0	Operating hours - device 4
xUpdate	BOOL			Trigger recalculation of the sequence on every rising edge

Outputs

Name	Data type	Value range	Initial value	Function
udiCurrentSequence	UDINT		0	Current device sequence as integer
sCurrentSequence	STRING		‘’	Current device sequence as string
wNumberOfOperationalDevices	WORD		0	Number of operational-ready devices
xCmd1	BOOL		FALSE	Enable - device 1 ( TRUE = enable )
xCmd2	BOOL		FALSE	Enable - device 2 ( TRUE = enable )
xCmd3	BOOL		FALSE	Enable - device 3 ( TRUE = enable )
xCmd4	BOOL		FALSE	Enable - device 4 ( TRUE = enable )
wPrio1	WORD		0	Current priority of device 1 ( 0 = none, 1 - 3 )
wPrio2	WORD		0	Current priority of device 2 ( 0 = none, 1 - 3 )
wPrio3	WORD		0	Current priority of device 3 ( 0 = none, 1 - 3 )
wPrio4	WORD		0	Current priority of device 4 ( 0 = none, 1 - 3 )
xErr	BOOL		FALSE	Output - fault
eOperationalCondition	eRedundance3_OperationalMode			Number / name of the current operating condition

Setpoints / parameters

Name	Data type	Value range	Initial value	Function
xConOperatingHours	BOOL		TRUE	FALSE = follower switching only allowed via input xUpdate, TRUE = follower switching automatic after operating hours
xEnFb	BOOL		TRUE	FALSE = switching based on enable ( xCmdX ), TRUE = switching based on running signal ( xFbX )
wTolerance	WORD		100	Threshold - operating hours difference for direct follower change in partial load operation

Function description

General

This function block is used for the redundant control of 0 - 4 identical devices depending on the influencing variables Demands ( wActiveNumberOfDevices ), operating hours ( uiOperatingHours ), operating states ( xFb ) and fault states ( xAlarm ).\

Input wActiveNumberOfDevices

This input is used to set the number of devices that should currently be used. Permitted range: 0 - 4\

Input xUpdate

Each rising edge on this input triggers a recalculation of the current device sequence. Boundary conditions: xConOperationHours = FALSE, operating hours difference = 0 hours.\

Output udiCurrentSequence

This output always shows the current device sequence as an integer. The number of the device with the highest priority is always at the beginning, then follows the number of the device with the second highest priority, etc. Example: udiCurrentSequence = 145 means: device 1 = priority 1, device 4 = priority 2 and device 5 = priority 3\

Output sCurrentSequence

This output always shows the current device sequence as a string with separators. The same priority rules apply as for the output udiCurrentSequence. Example: sdiCurrentSequence = ‘1-4-5’ means: device 1 = priority 1, device 4 = priority 2 and device 5 = priority 3\

Output wNumberOfOperationalDevices

This output always shows the number of operational-ready devices.\

Output fault xErr

This output is active ( = TRUE ) if at least one of the following conditions is met.\

1. wActiveNumberOfDevices > wTotalMumberOfDevices\

In all other cases the output *xErr* is not active ( = FALSE ).\

Output eOperationalCondition

This output always represents the current load situation ( idle, partial load, full load ) depending on the setpoint / parameter xEnFb thereof. xEnFb = FALSE: The enable outputs xCmd of the operational-ready devices are evaluated / considered. xEnFb = TRUE: The running states xFb of the operational-ready devices are evaluated / considered. Example: xEnFb = TRUE and xFb1 = TRUE and xFb2 = TRUE: Output = PartLoad_Inputs_Fb\

Setpoint / parameter xConOperatingHours

xConOperatingHours = FALSE: Switching of the device sequence is only triggered by a rising edge on input xUpdate triggered. xConOperatingHours = TRUE: Switching of the device sequence is triggered depending on operating hours, running signals ( when xEnFb = TRUE ) and the enables ( when xEnFb = FALSE ) is triggered.\

Setpoint / parameter xEnFb

xEnFb = FALSE: The enable outputs ‘xCmd’ of the operational-ready devices are evaluated / considered. xEnFb = TRUE: The running states ‘xFb’ of the operational-ready devices are evaluated / considered.\

Setpoint / parameter wTolerance

This setpoint determines the maximum operating hours difference before switching the device sequence due to operating hours. \

Determination of the device sequence

A change of the device sequence can generally only occur if at least one of the following conditions is met: \

1. The fault state of at least one device has changed ( high priority )\

2. The operating hours of at least one ready-for-operation device have changed ( low priority )\

Definition - Idle: **xEnFb** = FALSE: The enable outputs ‘xCmd’ of all ready-for-operation devices are inactive ( = FALSE ) **xEnFb** = TRUE: The status signals ‘xFb’ of all ready-for-operation devices are inactive ( = FALSE ) Definition - Full load: **xEnFb** = FALSE: The enable outputs ‘xCmd’ of all ready-for-operation devices are active ( = TRUE ) **xEnFb** = TRUE: The status signals ‘xFb’ of all ready-for-operation devices are active ( = TRUE ) Definition - Partial load: **xEnFb** = FALSE: The number of enable outputs *xCmd* of all ready-for-operation devices in the active state ( = TRUE ) is greater than/equal to 1 and less than the number of all ready-for-operation devices **xEnFb** = FALSE: The number of status signals *xFb* of all ready-for-operation devices in the active state ( = TRUE ) is greater than/equal to 1 and less than the number of all ready-for-operation devices Switching with **high** priority ( = immediate ) depending on fault states ( inputs *xAlarm* ) The fault state of each device in the range 1 - 4 is recorded cyclically and evaluated for changes. Any faulty device in the range 1 - 4 ( input *xAlarm* = TRUE ) is no longer ready for operation. Any change in the fault state of at least one device in the range 1 - 4 triggers an immediate recalculation of the device sequence. Switching with **low** priority depending on operating hours ( inputs *udiOperationHours* ), operating states ( inputs *xFb* ) and enable outputs ( outputs *xCmd* ) of devices 1 - 4. The operating hours of each ready-for-operation device in the range 1 - 4 are recorded cyclically and evaluated for changes. The operating states and enable outputs of each ready-for-operation device in the range 1 - 3 are recorded cyclically. The recalculation of the device sequence occurs as soon as one of the situations described below is given: **Situation 1** ( *xConOperationHours* = FALSE, rising edge at input *xUpdate* ) A recalculation of the device sequence is performed with an operating hours difference of 0 hours, i.e. the non-faulty device with the lowest operating hours has the highest priority ( in case of equal operating hours the device with the lower number has the higher priority ). **Situation 2** ( *xConOperationHours* = TRUE, Idle or Full load ) In idle or under full load a recalculation of the device sequence is performed with an operating hours difference of 0 hours, i.e. the non-faulty device with the lowest operating hours has the highest priority ( in case of equal operating hours the device with the lower number has the higher priority ). The recalculation of the device sequence is triggered if the operating hours of at least one ready-for-operation device have changed. **Situation 3** ( *xConOperationHours* = TRUE, Partial load ) When first switching to partial load operation a recalculation of the device sequence is performed with an operating hours difference of 0 hours, i.e. the non-faulty device with the lowest operating hours has the highest priority ( in case of equal operating hours the device with the lower number has the higher priority ). In regular partial load operation a recalculation of the device sequence is performed with an operating hours difference of **wTolerance** hours. The recalculation of the device sequence is triggered if the operating hours of at least one ready-for-operation device have changed. \

Enable outputs xCmd

The states of the outputs of the devices in the range 1 - 4 are finally determined as follows: The enable outputs of the ready-for-operation devices in the range 1 - 4 are activated if their current priority <= the number of requested devices ( input *wActiveNumberOfDevices* ). The enable outputs of the ready-for-operation devices in the range 1 - 4 are deactivated if their current priority > the number of requested devices ( input *wActiveNumberOfDevices* ). \

Priority outputs wPrio

The priority outputs of each device always contain the current priority in the range 0 - 4. Priority = 0: The device has no or an invalid priority Priority = 1: The device has the highest priority Priority = 2: The device has the second highest priority Priority = 3: The device has the third highest priority Priority = 4: The device has the fourth highest priority\

CODESYS

InOut:

Scope	Name	Type	Initial
Input	wActiveNumberOfDevices	WORD	0
Input	xFb1	BOOL	FALSE
Input	xFb2	BOOL	FALSE
Input	xFb3	BOOL	FALSE
Input	xFb4	BOOL	FALSE
Input	xAlarm1	BOOL	TRUE
Input	xAlarm2	BOOL	TRUE
Input	xAlarm3	BOOL	TRUE
Input	xAlarm4	BOOL	TRUE
Input	udiOperatingHours1	UDINT	0
Input	udiOperatingHours2	UDINT	0
Input	udiOperatingHours3	UDINT	0
Input	udiOperatingHours4	UDINT	0
Input	xUpdate	BOOL
Input Const	xConOperatingHours	BOOL	TRUE
Input Const	xEnFb	BOOL	FALSE
Input Const	wTolerance	WORD	100
Output	udiCurrentSequence	UDINT	0
Output	sCurrentSequence	STRING	‘’
Output	wNumberOfOperationalDevices	WORD	0
Output	xCmd1	BOOL	FALSE
Output	xCmd2	BOOL	FALSE
Output	xCmd3	BOOL	FALSE
Output	xCmd4	BOOL	FALSE
Output	wPrio1	WORD	0
Output	wPrio2	WORD	0
Output	wPrio3	WORD	0
Output	wPrio4	WORD	0
Output	xErr	BOOL	FALSE
Output	eOperationalCondition	eRedundance3_OperationalMode