[W_A] Write analog

Function block W_A updates properties 'Present value' and 'Reliability' from the calculated value, simple process value and simple process value reference objects with a present value of data type Real.

W_A updates the following properties:

Functioning

Compatible data points:

  • Analog calculated value [ACalcVal]
  • Analog simple process value [ASmpPrcVal]
  • Analog simple process value reference [ASmpPrcValR]

Required properties:

  • Present value
  • Tracking value (for calculated value objects only)
  • Status flag
  • Reliability

Optional properties:

  • Extension by event configuration
  • Event state
  • Acknowledged transitions
  • Extension by data aggregation
  • Maintenance state
  • Operating hours
  • Suppress event notification
  • Suppress event detection
  • Enable aggregation
Pins

Input

Description

Data type

Default value
Value range

EnWrit

Enable write

If [EnWrit] = 1, writing values from inputs [Val] and [SetValid] to the BACnet object is enabled.
If [EnWrit] changes from 0 to 1, writing occurs.

Boolean

1

Val

Value

Virtual value, calculated and assigned by the control program to update the present value.

[Val] updates the following property:

  • 'Tracking value' for calculated value objects; the BACnet object then internally updates the present value with the written value.
  • 'Present value' for simple process value objects.
  • 'Present value' for simple process value reference objects.

[Val] is written if [EnWrit] = 1 and one of the following items appears:

  • [Val] changes with value
    • Greater than or equal to [TshVal].
    • Equal to the limit values 0.0 or 100.0 ([TshVal] is ignored).
  • [SetValid] changes (for calculated value objects only).
  • [RptWrit] is 1.

Real

0.0

SetValid

Set valid value indication

A value calculated and assigned by the control program that indicates whether [Val] is reliable.

[SetValid] is mapped to an error code that updates 'Reliability' if [EnWrit] = 1 and one of the following items applies:

  • [SetValid] changes.
  • [Val] changes.
  • [RptWrit] is 1.

Note
The value from [SetValid] is only written on data points of type calculated value to property 'Reliability'.

Boolean

1

0 - Reliability error code 7 (unreliable - other).
1 - Reliability error code 0 (no fault).

RptWrit

Repeat write

Forces writing of [Val] (and [SetValid]) to the data point. Writing is repeated in each programming cycle, if [RptWrit] = 1.
[RptWrit] typically is calculated and set by the control program.

Note:
[RptWrit] cannot be permanently forced to 1. This may influence performance and communications traffic.

Boolean

0

0 - No action.
1 - Writes [Val] (and [SetValid]) to the data point for each program cycle.

TshVal

Threshold value

Configured value to control function block write attempts. An attempt is only permitted if the change of value is greater than or equal to [TshVal].
Exception: [TshVal] is ignored if the new value is a limit value such as 0.0 or 100.0.

Note
Cannot be set to 0.0.

Real

0.1

SupEvtDet

Suppress event detection

Suppresses the detection of events.
Note
If the extension for 'Intrinsic reporting' is not enabled, the input value is not considered in the function of the function block.
If the same BACnet object is accessed by multiple functions in a control program, only one of these function blocks may interconnect to the pin.
The function is not available for BACnet third-party objects.

Boolean

0

SupEvtNtf

Suppress event notification

Suppresses notification of events.
Note
If the extension for 'Intrinsic reporting' is not enabled, the input value is not considered in the function of the function block.
If the same BACnet object is accessed by multiple function blocks in the control program, only one of these function blocks may interconnect to the pin.
The function is not available for BACnet third-party objects.

Boolean

0

EnDataAgn

Enable data aggregation

Permits activation or deactivation of data aggregation.
Note
If the extension for data aggregation is not enabled, the input value is not considered in the function of the function block.
If the same BACnet object is accessed by multiple blocks in the control program, only one of these function blocks may interconnect to the pin.
The function is not available for BACnet third-party objects.

Boolean

0

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

PrVal

Present value

Value of property 'Present value' for the referenced BACnet object. [PrVal] supplies the last valid value in the event of a fault.

Real

0.0

Dstb

Disturbed

[Dstb] indicates whether the referenced BACnet object is in fault or in state OffNormal. When the BACnet object returns to state Normal, [Dstb] retains its value until the transition to normal is acknowledged.
[Dstb] = 1, if:
BACnet object = Access error
OR
'Status flag' = Fault
OR
'Event state' <> Normal

[Dstb] = 0, if the above condition is not fulfilled AND 'Acknowledged transitions' = x, x, 1.

Note
Properties 'Event state' and 'Acknowledged transitions' are not considered if the BA-Object has an alarm extension set to disabled.
Output [Dstb] does not retain the value after a restart following a power outage if the state of the BACnet object is normal.
Properties 'Event state' and 'Acknowledged transitions' are not considered on BACnet third-party objects.

Boolean

0

Flty

Faulty

[Flty] indicates whether the last event on the referenced BACnet object was in fault. If the BACnet object returns to the normal state, [Flty] retains its value until the transition to normal is acknowledged.
[Flty] = 1, if:
BACnet object = Error during access
OR
'Status flag' = Fault

[Flty] = 0, if the above condition is not fulfilled AND one of the following possibilities is valid:

  • 'Event state' = Upper limit
  • OR
  • 'Event state' = Lower limit
  • OR
  • 'Event state' = Normal AND 'Acknowledged transitions' = x, x, 1

Note
Properties 'Event state' and 'Acknowledged transitions' are not considered if the BA-Object has an alarm extension set to disabled.
Output [Flty] does not retain the value upon restart after a power outage if the state of the BACnet object is normal.
Properties 'Event state' and 'Acknowledged transitions are not considered for BACnet third-party objects.

Boolean

0

HiLmRd

High limit reached

Indicates if the last event on the referenced BACnet object has state Offnormal based on reaching the upper limit. When the BACnet object returns to state Normal, [HiLmRd] retains its value until the transition to normal is acknowledged.
[HiLmRd] = 1, if:
BACnet object = Access successful
AND
'Status flag' = No fault
AND
'Event state' = Upper limit

[HiLmRd] = 0, if the above condition is not fulfilled OR one of the following possibilities is valid:

  • 'Event state' = Lower limit
  • 'Event state' = Normal AND 'Acknowledged transitions' = x, x, 1

Note
Properties 'Event state' and 'Acknowledged transitions' are not considered if the BA-Object has an alarm extension set to disabled.
Output [HiLmRd] does not retain the value upon restart after a power outage if the state of the BACnet object is normal.
The function is not available for BACnet third-party objects.

Boolean

0

LoLmRd

Low limit reached

Indicates if the last event on the referenced BACnet object has state Offnormal based on reaching the lower limit. If the BACnet object returns to state Normal, [LoLmRd] retains its value until the transition to normal is acknowledged.
[LoLmRd] = 1, if:
BACnet object = Access successful
AND
'Status flag' = No fault
AND
'Event state' = Lower limit

[LoLmRd] = 0, if the above condition is not fulfilled OR one of the following possibilities is valid:

  • 'Event state' = Upper limit
  • 'Event state' = Normal AND Acknowledged transitions = x, x, 1.

Note
Properties 'Event state' and 'Acknowledged transitions' are not considered if the BA-Object has an alarm extension set to disabled.
Output[LoLmRd] does not retain the value upon restart after a power outage if the state of the BACnet object is normal.
The function is not available for BACnet third-party objects.

Boolean

0

Rlb

Reliability
Indicates the value of property 'Reliability', if the property is available.

Integer

0: No fault detected

Oph

Operating hours

Displays the value of the property operating hours for the referenced BACnet object
Note
The output is set to 0, if the extension for data aggregation is disabled or the property does not exist. The function is not available for BACnet third-party objects.

Double Word

0

MntnSta

Maintenance state

Supplies the value for property 'Maintenance state' for the referenced BACnet object.

Integer

1

1: None
2: Limit present period exceeded
3: Limit exceeded

Note
The output is set to 1 if the extension for data aggregation is disabled or the property does not exist.
The function is not available for BACnet third-party objects.

ErrCode

Error code indication

Integer

0: No error

= 0 - No error
> 0 - XFB error codes

Troubleshooting

The write function is unavailable if a data point of type calculated value is located on another device.