Credential Data Input

A Credential Data Input models a reader that supplies authentication factors, such as a card reader, keypad or biometric reader. Each time someone presents a credential, the object holds what was read. An access system uses it to decide who is at the door.

Typical uses

• A card reader at a door
• A PIN keypad
• A fingerprint reader
• A Wiegand reader on an access controller

Key properties

Property	What it holds
Present_Value	The authentication factor from the most recent read.
Supported_Formats	The credential formats this reader understands.
Supported_Format_Class	The class of format the reader supports, when formats are grouped.
Update_Time	When Present_Value last changed. Clients use it to spot a new read.

How it behaves

Clients can subscribe to Present_Value, Status_Flags and Update_Time. The object applies no event algorithm. With intrinsic reporting it reports faults only, and its Event_State shows FAULT while a Reliability fault is held.

With the CAS BACnet Stack

Enable it with the STACK_OPTION_OBJECT_TYPE_CREDENTIAL_DATA_INPUT build option and add each object with BACnetStack_AddObject. Supported_Formats is an array that you serve through the callback you register with BACnetStack_RegisterCallbackGetPropertyAuthenticationFactorFormat. The stack calls it once per element, and a conformant object needs it. Register it before clients read the object. For fault reporting, call BACnetStack_SetAlarmsAndEventsForObjectEnabled.

Related object types

Access Point, Access Credential, Access Door, Access User

Properties

The properties ASHRAE 135-2024 clause 12.36 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.
Present_Value	BACnetAuthenticationFactor	R1	yes	no (yes while Out_Of_Service is true)	No default: value-not-initialized.
Description	CharacterString	O	no	no	""
Status_Flags	BACnetStatusFlags	R	yes	no	Built by the stack from your callbacks.
Reliability	BACnetReliability	R1	yes	no (yes while Out_Of_Service is true)	0
Out_Of_Service	Boolean	R	yes	no	false
Supported_Formats	BACnetARRAY[N] of BACnetAuthenticationFactorFormat	R	yes	no	No default: the read fails.
Supported_Format_Classes	BACnetARRAY[N] of Unsigned	O2	no	no	0
Update_Time	BACnetTimeStamp	R	yes	no	A date-time stamp with every octet X'FF' (no update yet).
Event_Detection_Enable	Boolean	O3,4	no	no	false
Notification_Class	Unsigned	O3,4	no	no	0
Event_Enable	BACnetEventTransitionBits	O3,4	no	no	An empty bit string.
Event_State	BACnetEventState	O3,4	no	no	0
Acked_Transitions	BACnetEventTransitionBits	O3,4	no	no	An empty bit string.
Notify_Type	BACnetNotifyType	O3,4	no	no	0
Event_Time_Stamps	BACnetARRAY[3] of BACnetTimeStamp	O3,4	no	no	No default: the read fails.
Event_Message_Texts	BACnetARRAY[3] of CharacterString	O4	no	no	""
Event_Message_Texts_Config	BACnetARRAY[3] of CharacterString	O4	no	no	""
Reliability_Evaluation_Inhibit	Boolean	O	no	no	false
Property_List	BACnetARRAY[N] of BACnetPropertyIdentifier	R	yes	no	Held by the stack.
Audit_Level	BACnetAuditLevel	O5	not in profile	not in profile	No default: the read fails.
Auditable_Operations	BACnetAuditOperationFlags	O5	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	""