BACnetStack_SetCOVSettings

bool BACnetStack_SetCOVSettings(
  const uint32_t deviceInstance,
  const uint32_t maxNumberOfSubscriptions,
  const uint32_t maxSupportedCOVLifetime);

Sets the COV subscription-table capacity and the maximum supported COV lifetime for subscriptions received by this device.

maxNumberOfSubscriptions is applied as BACnetStack_SetMaxActiveCOVSubscriptions() applies it: to the SubscribeCOV / SubscribeCOVProperty table AND, in a build with SubscribeCOVPropertyMultiple, to the SubscribeCOVPropertyMultiple table. Call BACnetStack_SetCOVMultipleSettings() AFTER this function to give the SubscribeCOVPropertyMultiple table a different capacity.

The lifetime is a single device-wide bound shared by SubscribeCOV, SubscribeCOVProperty and SubscribeCOVPropertyMultiple.

ENFORCEMENT IS REJECT, NOT CLAMP. A subscription request asking for a lifetime longer than maxSupportedCOVLifetime is answered with Error(services, valueOutOfRange); it is not silently shortened to the maximum.

THE DEVICE DEFAULT IS 28800 SECONDS (8 hours) - MAX_SUPPORTED_COV_LIFETIME in BACnetStackConstants.h, the minimum the BACnet spec requires a device to support. Every device starts at that value, so it is what the stack enforced before this setter was called.

PASS 0 FOR “USE THE DEVICE DEFAULT”. 0 is accepted as a sentinel and substitutes 28800, so a caller does not need to know the number. Passing 28800 explicitly is identical.

maxNumberOfSubscriptions = 0 means NO LIMIT.

THIS FUNCTION IS NOT ATOMIC. It applies maxNumberOfSubscriptions first, then maxSupportedCOVLifetime; if the second application fails, the first has ALREADY taken effect and this still returns false - the caller cannot tell a total failure from a half-applied one. The two settings are independent, so prefer the single-purpose BACnetStack_SetMaxActiveCOVSubscriptions() and BACnetStack_SetMaxSupportedCOVLifetime() below, each of which is unambiguous about what it changed. This function is kept for compatibility with its existing partial-application behaviour.

Note

Requires one of the build options STACK_OPTION_DS_COVU_B, STACK_OPTION_DS_COV_SUBSCRIBE_COV (any of them turns on STACK_OPTION_SUBSCRIBE_COV, the macro this function checks).

BACnet reference: ANSI/ASHRAE 135-2024 clause 13.1 (Change of Value Reporting).

Parameters

Parameter	Direction	Description
deviceInstance	in	The instance of the device to set the maximum supported COV lifetime.
maxNumberOfSubscriptions	in	The maximum number of active COV subscriptions to support. If set to zero, no limit.
maxSupportedCOVLifetime	in	The maximum supported COV lifetime in seconds. Valid range is 0 .. MAX_UINT32 - 1; exactly MAX_UINT32 is rejected. Pass 28800 for the device default. See the note above before passing 0.

Returns

True if successful, false if failed.

Topic: Device and services. Declared in CASBACnetStackDLL.h.