Handler-to-Object Interface Functions

Functions
uint32_t	Device_Object_Instance_Number (void)
int	Device_Read_Property (BACNET_READ_PROPERTY_DATA *rpdata)
void	Device_Init (object_functions_t *object_table)

Detailed Description

This section describes the fairly limited set of functions that link the BAC-stack handlers to the BACnet Object instances. All of these calls are situated in the Device Object, which "knows" how to reach its child Objects.

Most of these calls have a common operation:

1. Call Device_Objects_Find_Functions( for the desired Object_Type )
   • Gets a pointer to the object_functions for this Type of Object.
2. Call the Object's Object_Valid_Instance( for the desired object_instance ) to make sure there is such an instance.
3. Call the Object helper function needed by the handler, eg Object_Read_Property() for the RP handler.

Function Documentation

uint32_t Device_Object_Instance_Number

(

void

)

Return the Object Instance number for our (single) Device Object. This is a key function, widely invoked by the handler code, since it provides "our" (ie, local) address.

Returns

The Instance number used in the BACNET_OBJECT_ID for the Device.

int Device_Read_Property

(

BACNET_READ_PROPERTY_DATA *

rpdata

)

Looks up the requested Object and Property, and encodes its Value in an APDU.

If the Object or Property can't be found, sets the error class and code.

Parameters

rpdata

[in,out] Structure with the desired Object and Property info on entry, and APDU message on return.

Returns

The length of the APDU on success, else BACNET_STATUS_ERROR

void Device_Init

(

object_functions_t *

object_table

)

Initialize the Device Object. Initialize the group of object helper functions for any supported Object. Initialize each of the Device Object child Object instances.

Parameters

object_table

[in,out] array of structure with object functions. Each Child Object must provide some implementation of each of these functions in order to properly support the default handlers.

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