BACnetRetrievePropertyInstance (FUN)

FUNCTION BACnetRetrievePropertyInstance : IEC_BACNET_STATUS

Reads a property value from the BACnet server database.

This routine extracts the value stored in the BACnet server database for the given property. This routine carries some similarity with BACnetReadProperty, but it significantly differ in the way it performs the operation and may give the different result. While BACnetRetrievePropertyInstance extracts the value for the given property from the BACnet server database, BACnetReadProperty will send a Read-Property request.

InOut:

Scope	Name	Type	Comment
Return	BACnetRetrievePropertyInstance	IEC_BACNET_STATUS	A status indicating if the operation worked.
Input	deviceInstNumber	IEC_BACNET_DWORD	Instance number of a Device Object.
	pObjectID	POINTER TO IEC_BACNET_OBJECT_ID	A pointer to the Object Identifier.
	propID	IEC_BACNET_PROPERTY_ID	The Property identifier of the local property.
	nIndex	DINT	Use array-indices for specific element of an array property. If the array index is not available, an error is returned. You can use -1 for non array properties. Indizes count from 1. Using -1 for array properties indicates reading the whole array.
	pVal	POINTER TO IEC_BACNET_PROPERTY_CONTENTS	Pointer to a Property Contents containing a buffer into which to copy the value. Upon successful completion of this routine, the Property Contents tag attribute indicates the type of the Property. The application may initialize the buffer size with 0 and pointer with NULL. In this case the API will allocate the memory needed to store the value and the application must release it.