[LNGR_PRD] Lingering of a period

The function block LNGR_PRD records the lingering period in hours during which a signal moves within freely definable limits (5 ranges).

LNGR_PRD records the lingering period in hours during which a signal moves within freely definable limits (5 ranges).

Functioning

Enable and disable the function

The lingering period is determined (in hours) if the function is enabled (EnFnct and EnEvl = 1) and the analog input signal [In] is reliable (Vldty = 1). The analog value lingers between freely definable limit value ranges.

Calculation and evaluation

Evaluation kind [EvlKind] determines the method of calculation. [HiLm] and [LoLm] determine the addition or subtraction of the Delta ranges [DRng1] and [DRng2] for the limit value ranges. For enabled function and reliable input signal, the time for each evaluation kind (see illustration) is added up and displayed in hours at outputs [PrLgrrx] and [RctLgrrx]. The times are distributed accordingly for a changeover of [EvlKind].

PrLgrrX	Present Linger in Range X
RctLgrrX	Recent Linger in Range X

Evaluation Kind 1 (Low to high)	Evaluation Kind 2 (Low and high)	Evaluation Kind 3 (Individual)
PrLgrr1 = 10,6h RctLgrr1 = 13,7h	PrLgrr1 = 3,6h RctLgrr1 = 8h	PrLgrr1 = 0h RctLgrr1 = 8h
PrLgrr2 = 6,2h RctLgrr2 = 5,7h	PrLgrr2 = 3h RctLgrr2 = 2,5h	PrLgrr2 = 0h RctLgrr2 = 2,5h
PrLgrr3 = 4h RctLgrr2 = 3,2h	PrLgrr3 = 4h RctLgrr2 = 3,2h	PrLgrr3 = 4h RctLgrr2 = 3,2h
PrLgrr4 = -1h RctLgrr4 = -1h	PrLgrr4 = -1h RctLgrr4 = -1h	PrLgrr4 = 3h RctLgrr4 = 0h
PrLgrr5 = -1h RctLgrr5 = -1h	PrLgrr5 = -1h RctLgrr5 = -1h	PrLgrr5 = 3,6h RctLgrr5 = 0h

The deviation for the present time period is displayed on [PrLgrrx]. After the time period has expired, the present times are saved as times for the recent time period [RctLgrrx] and set to zero. The time period, generated outside of LNGR_PRD, is determined via a rising slope on the input [Imp]. If the input signal is invalid (Vldty = 0), the calculation stops. The recent valid values from the outputs are frozen until the signal is valid again.

Subperiods within time periods

Input [EnEvl] can be used to evaluate subperiods within the entire time period. When EnEvl = 0, the evaluation is disabled and the recent valid values are displayed at the outputs. At a pulse, the present times are saved as values from the last time period.

Reset

All present and recent values are set to zero via a rising slope on input [Reset].

Pins

Input	Description	Data type	Default value Value range
EnFnct	Enable function	Boolean	1
EnFnct	0 - The function is disabled (All [PrLgrrx] and [RctLgrrx] = 0). 1 - The function is enabled.
EnEvl	Enable evaluation	Boolean	1
EnEvl	0 - Evaluation is disabled and the valid values at the outputs are frozen. 1 - Evaluation is enabled
In	Input Input signal	Real	0.0
Imp	Impulse Pulse input for which the evaluation time period is determined. The rising edge indicates start of new period.	Boolean	0
Imp	0 - No 1 - Yes
Vldty	Validity The calculation of the linger period can only be calculated with a valid input signal.	Boolean	1
Vldty	0 - Input signal is not valid. 1 - Input signal is valid.
EvlKind	Evaluation kind	Integer	3: On 1...3
EvlKind	1: Unknown 2: Off 3: On
HiLm	High limit	Real	23.0
LoLm	Low limit	Real	21.0
DRng1	Delta range 1	Real	2.0
DRng2	Delta range 2	Real	4.0
Reset	Reset All times are reset to zero.	Boolean	0
Reset	0 - No 1 - Yes
Pers	Persistent	Boolean	0
Pers	0 - No 1 - Yes: the values are stored persistently.
TshVal	Threshold value	Real	0.1
BaObjRef	BA-Object reference Link between function block and BACnet object.	Structure	---
BaObjRef > DeviceID	Device identifier [DeviceID] includes object type and object instance in one ID. Identifies the device object: local or remote. A local device object can also be identified by value 16#3FFFFF.	Double Word	16#3FFFFF
BaObjRef > ObjectID	Object identifier [ObjectID] includes object type and object instance in one ID. Identifies the object on a device.	Double Word	16#3FFFFF
BaObjRef > ItemID	Item identifier [ItemID] represents an index in a view node object that references the BACnet object. [ObjectID] and [ItemID] together define an indirect reference to the BACnet object. Value -1 indicates a direct interface.	Integer	-1

Output	Description	Data type	Default value Value range
PrLgrr1	Present linger in range 1	Real	0.0
RctLgrr1	Recent linger in range 1	Real	0.0
PrLgrr2	Present linger in range 2	Real	0.0
RctLgrr2	Recent linger in range 2	Real	0.0
PrLgrr3	Present linger in range 3	Real	0.0
RctLgrr3	Recent linger in range 3	Real	0.0
PrLgrr4	Present linger in range 4	Real	0.0
RctLgrr4	Recent linger in range 4	Real	0.0
PrLgrr5	Present linger in range 5	Real	0.0
RctLgrr5	Recent linger in range 5	Real	0.0
Dstb	Disturbed [Dstb] indicates whether the referenced BACnet object was accessed. [Dstb] = 0, if: BACnet object access = Access successful [Dstb] = 1, if: BACnet object access = Error during access	Boolean	0
ErrCode	Error code indication	Integer	0: No error
ErrCode	= 0 - No error > 0 - Error codes

Application

LNGR_PRD is used to calculate the linger period (hours) for an analog input value in a freely definable range within a time period. By recognizing setpoint deviations and determining how long a value lingers within the freely definable limit value range for a specified time period, errors, such as wrong control parameters, setpoint violations or manual interventions, can be identified earlier.

The following example is based on an evaluation period = 1 day: