BACnetStack_DecodeAs

uint32_t BACnetStack_DecodeAs(
  const uint8_t decodeType,
  const char * inMessageRaw,
  const uint16_t inMessageLength,
  char * outMessage,
  const uint32_t outMessageMaxLength,
  const uint8_t packetNetworkType);

Decodes a raw BACnet message into a human-readable rendering of the packet, for debugging, logging, and client-side inspection of inbound messages.

Replaces the two older decode exports, one per format, which differed only in their renderer. Pass the format as the first argument:

BACnetStack_DecodeAs(BACnetDecodeType_JSON, raw, rawLen, out, sizeof(out), packetNetworkType);

Sizing the output buffer: renderings are much larger than the wire message. A ReadPropertyMultiple response can exceed 20 KB; 64 KB is a safe general-purpose buffer. If the rendering does not fit, NOTHING is written and the function returns 0 - it does not truncate, and the return value does not tell you how much space would have been needed.

Compile-time gating: XML requires STACK_OPTION_DECODE_AS_XML, JSON requires STACK_OPTION_DECODE_AS_JSON, and BOTH require STACK_OPTION_STRING_LITERALS. The two format options remain independent, so a build can include one renderer and not the other; asking for a format that was not compiled in returns 0 and logs.

Parameters

Parameter	Direction	Description
decodeType	in	The output format. See BACnetDecodeType.
inMessageRaw	in	The raw BACnet message.
inMessageLength	in	The length of the BACnet message.
outMessage	out	The resulting rendered output. Not null-terminated; use the return value as the length.
outMessageMaxLength	in	The maximum buffer length for the rendered output.
packetNetworkType	in	The BACnet network type the raw message came from: 0 = BACnet/IP, 1 = MS/TP, 2 = BACnet/SC, 3 = BACnet/IPv6 (a build with STACK_OPTION_DATA_LINK_LAYER_IPV6; the raw message is then the NPDU and APDU, as for MS/TP, without the BVLL header) (the stack’s packet network types, as BACnetStack_AddRouterPort() takes; not BACnetNetworkType, where IPv4 is 5). This is the one deliberate exception to the Network Port instance convention every other Send/Receive export follows: DecodeAs is a pure decoder that can be handed bytes captured from a transport this device does not itself have a Network Port object for (e.g. a packet capture from another device), so it takes the 3-valued transport-type enum directly rather than resolving a claimed instance.

Returns

The number of bytes written to outMessage, or 0 on any failure (unknown decodeType, format not compiled in, invalid packetNetworkType, undecodable message, or buffer too small).

Topic: Client requests. Declared in CASBACnetStackDLL.h.