Reject APDUs are sent when a confirmed service request cannot even be interpreted because of a protocol or syntactical error.

APDU Description (ASHRAE 135)

The BACnet-Reject-PDU is used to reject a received confirmed service request based on syntactical flaws or other protocol errors that prevent the PDU from being interpreted or the requested service from being provided. Only confirmed request PDUs may be rejected. A Reject APDU shall be sent only before the execution of the service. (Clause 18.8)

Per ASHRAE 135, a Reject must only be generated before the service is executed. If the service started running and then failed, an Error APDU (or possibly Abort) is the correct reply.

Common reject reasons (see BACnet.Protocol.Constants.reject_reason/0 and Clause 18.8 "Reject Reason"):

• :other, :buffer_overflow
• :inconsistent_parameters, :invalid_tag, :missing_required_parameter
• :invalid_apdu_in_this_state

This module implements the BACnet.Stack.EncoderProtocol.

Decoding is performed by BACnet.Protocol.APDU.decode/1 (and BACnet.Protocol.APDU.decode_reject/1).

Examples

iex> reject = %Reject{invoke_id: 9, reason: :buffer_overflow}
iex> Reject.encode(reject)
{:ok, <<96, 9, 1>>}

Decoding:

iex> raw = <<0x60, 0x09, 0x01>>
iex> {:ok, %Reject{invoke_id: 9, reason: :buffer_overflow}} = BACnet.Protocol.APDU.decode(raw)