Pulse Converter

A Pulse Converter object turns a stream of pulses into a scaled number. It counts pulses from a meter or an accumulator, multiplies by a scale factor, and presents the result in engineering units. A client can also adjust the count to match a meter reading.

Typical uses

• Electric meter pulses converted to kWh
• Water meter pulses converted to litres
• Gas meter counts for demand tracking
• Reading from an accumulator in the same device
• Peak-load monitoring over a time interval

Key properties

Property	What it holds
Present_Value	The scaled value, calculated from Count and Scale_Factor.
Input_Reference	The property that supplies the pulses, for example an accumulator’s value in the same device.
Scale_Factor	The factor that turns a count into engineering units.
Adjust_Value	Writing it adjusts the count so Present_Value matches a known reading.
Count	The running pulse count since the last adjustment.
COV_Period	How often, in seconds, the object sends a COV notification even when the value has not moved far.

How it behaves

The object is not commandable. When it reports intrinsic events, the standard pairs it with the OUT_OF_RANGE algorithm, using High_Limit, Low_Limit and Deadband. COV notifications go out when Present_Value changes by COV_Increment, on any change to Status_Flags, or when COV_Period expires.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_PULSE_CONVERTOR build option, spelled that way, and add each object with BACnetStack_AddObject. Present_Value is a Real, so serve it with the callback you register with BACnetStack_RegisterCallbackGetPropertyReal. The other properties come from your callbacks, matched to their datatypes. To arm alarms, enable alarms for the object and call BACnetStack_SetIntrinsicOutOfRangeAlgorithm. Call BACnetStack_UpdateValue whenever the value you serve changes, so COV, trend logs and alarms see it.

Related object types

Accumulator, Analog Input, Analog Value

Properties

The properties ASHRAE 135-2024 clause 12.23 defines for this object type.

How to read the table:

• Conformance is what the standard asks of every object of this type: R is required, W is required and writable by a client, O is optional. A digit after the letter marks a condition in the standard that decides when the property is present or writable, such as support for intrinsic reporting.
• Present by default: yes means the stack presents the property as soon as you add the object; no means it is optional and you turn it on with BACnetStack_SetPropertyEnabled. This is the stack’s starting setup, so it can differ from the conformance code.
• Writable is whether a client can write the property by default. Change it with BACnetStack_SetPropertyWritable.
• not in profile means the stack does not offer this property for this object type.
• Value when your callback does not answer: “Held by the stack” means the stack stores and serves the value itself and does not ask your callbacks. Otherwise it is the value the stack answers when your callback declines or is not registered.

Property	Datatype	Conformance	Present by default	Writable	Value when your callback does not answer
Object_Identifier	BACnetObjectIdentifier	R	yes	no	Held by the stack.
Object_Name	CharacterString	R	yes	no	"Object <type>,<instance>", such as "Object 0,1" for Analog Input 1.
Object_Type	BACnetObjectType	R	yes	no	Held by the stack.
Description	CharacterString	O	no	no	""
Present_Value	Real	R1	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized.
Input_Reference	BACnetObjectPropertyReference	O	no	no	No default: the read fails.
Status_Flags	BACnetStatusFlags	R	yes	no	Built by the stack from your callbacks.
Event_State	BACnetEventState	R	yes	no	0
Reliability	BACnetReliability	O	no	no (yes while Out_Of_Service is true)	0
Out_Of_Service	Boolean	R	yes	no	false
Units	BACnetEngineeringUnits	R	yes	no	95 (no units)
Scale_Factor	Real	R	yes	no	0.0
Adjust_Value	Real	W	yes	yes	0.0
Count	Unsigned	R	yes	no	0
Update_Time	BACnetDateTime	R	yes	no	No default: the read fails.
Count_Change_Time	BACnetDateTime	R	yes	no	No default: the read fails.
Count_Before_Change	Unsigned	R	yes	no	0
COV_Increment	Real	O2	no	no	0.0
COV_Period	Unsigned	O2	no	no	0
Notification_Class	Unsigned	O3,5	no	no	0
Time_Delay	Unsigned	O3,5	no	no	0
High_Limit	Real	O3,5	no	no	0.0
Low_Limit	Real	O3,5	no	no	0.0
Deadband	Real	O3,5	no	no	0.0
Limit_Enable	BACnetLimitEnable	O3,5	no	no	An empty bit string.
Event_Enable	BACnetEventTransitionBits	O3,5	no	no	An empty bit string.
Acked_Transitions	BACnetEventTransitionBits	O3,5	no	no	An empty bit string.
Notify_Type	BACnetNotifyType	O3,5	no	no	0
Event_Time_Stamps	BACnetARRAY[3] of BACnetTimeStamp	O3,5	no	no	No default: the read fails.
Event_Message_Texts	BACnetARRAY[3] of CharacterString	O5	no	no	""
Event_Message_Texts_Config	BACnetARRAY[3] of CharacterString	O5	no	no	""
Event_Detection_Enable	Boolean	O3,5	no	no	false
Event_Algorithm_Inhibit_Ref	BACnetObjectPropertyReference	O5	no	no	No default: the read fails.
Event_Algorithm_Inhibit	Boolean	O5,6	no	no	false
Time_Delay_Normal	Unsigned	O5	no	no	0
Reliability_Evaluation_Inhibit	Boolean	O7	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O8	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O8	not in profile	not in profile	No default: the read fails.
Tags	BACnetARRAY[N] of BACnetNameValue	O	no	no	No default: the read fails.
Profile_Location	CharacterString	O	no	no	""
Profile_Name	CharacterString	O	no	no	""