3.18.0 Protocol Droid

Bugfixes

• Send frames with an APDU longer than 15 octets as L_Data_Extended frames. The Frame Type flag of Ctrl1 is now derived from the NPDU length when serializing a CEMILData instead of always being set to standard frame. This fixes sending telegrams over KNX Data Secure with a payload of 2 octets or more (eg. DPT 9.x or DPT 232.600) - Data Secure adds 12 octets to the plain APDU, which no longer fits in a standard frame. Sending an APDU longer than 254 octets now raises ConversionError instead of OverflowError.

Features

• Experimental. Add xknx.mcp, a host-agnostic subpackage of async MCP tool functions for the KNX bus and data point types (list_dpts, describe_dpt, encode_dpt_payload, decode_dpt_payload, get_connection_status, read_group_value, send_group_value_read, send_group_value_write). Frozen, JSON-native dataclass I/O with per-field descriptions in dataclasses.field metadata; carries no MCP SDK, Home Assistant or web-framework dependency, so a consumer wraps the functions into its own MCP transport. This subpackage is experimental and its API may change in a future release.

Protocol

• Reject incoming CEMI L_Data frames with a non-zero Extended Frame Format field with UnsupportedCEMIMessage. LTE-HEE frames use zone addressing, so their address fields can not be parsed as GroupAddress. The Frame Type flag is still not validated against the NPDU length when parsing - a receiver shall be tolerant towards the used frame format.
• CEMIFlags.EXTENDED_FRAME_FORMAT was removed; its value 0x0001 was reserved, not an "extended frame format" indicator - 0x0000 is used for standard frames as well as for long extended frames. CEMIFlags.LTE_FRAME_FORMAT and CEMIFlags.EXTENDED_FRAME_FORMAT_MASK were added instead.
• Add explicit length checks to every remaining APCI from_knx (and the top-level APCI.from_knx dispatcher) as defense-in-depth on top of the broad except (IndexError, struct.error, ValueError) added in 3.17.0: each service now raises ConversionError with a specific "Invalid length for A_X in CEMI" message for a truncated, malformed or overlong frame instead of relying solely on the generic dispatcher-level catch.