Documentation
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Overview ¶
Package mbus decodes M-Bus (Meter-Bus, EN 13757-2 link layer + EN 13757-3 application layer) frames — the European smart-metering protocol for electricity, gas, water, heat, and warm-water meters. The wired M-Bus link/application layers are shared with Wireless M-Bus (wM-Bus, 868 MHz), which a Flipper Sub-GHz capture can lift off the air; pasting the demodulated bytes here decodes the meter identity and command without a dedicated M-Bus master.
Wrap-vs-native judgement ¶
Native. M-Bus is defined by the public EN 13757 standard. The link layer is one of four fixed framings (single-character ACK, short, control, long), each a byte-counted structure with a trailing checksum and 0x16 stop byte. The application layer's Variable Data Structure carries a fixed header (BCD serial number, FLAG-encoded manufacturer, version, medium/device type, access number, status, signature) before the DIF/VIF data records. Every field is a fixed-format byte stream; dispatch is a set of small lookup tables.
What this package covers ¶
- Link-layer frame classification: single-character ACK (0xE5), short frame (0x10 ... 0x16), control frame (0x68 L L 0x68 ... 0x16 with L==3), long frame (0x68 L L 0x68 ... 0x16).
- L-field consistency (the two length bytes must match) and total-length validation against the buffer.
- Checksum verification (arithmetic sum of C..end-of-user-data mod 256) and the 0x16 stop byte.
- C-field (Control) function naming (SND_NKE, SND_UD, REQ_UD1, REQ_UD2, RSP_UD, ACK) plus the master↔slave direction bit.
- A-field (Address) value plus classification (unconfigured / primary / secondary-addressing / broadcast-no-reply / broadcast-all-reply / reserved).
- CI-field (Control Information) application-selector naming.
- Variable Data Structure fixed header (CI 0x72 long 12-byte / CI 0x7A short 4-byte): BCD identification (serial) number, FLAG-encoded 3-letter manufacturer, version, medium/device type with a name table, access number, status byte, signature.
What this package does NOT cover (deliberately out of scope) ¶
- DIF/VIF data-record decoding (the metering values themselves): the DIF data-field-coding × VIF unit/multiplier matrix is a substantial separate walker. The raw data-record bytes are surfaced so the operator can compare against EN 13757-3 §6.
- wM-Bus radio framing (mode S/T/C, 3-of-6 / Manchester line coding, block-wise CRC): feed already-demodulated/de-coded application bytes here.
- Encrypted application data (Mode 5 AES-CBC / Mode 7/9/13): the status/configuration field is surfaced but the ciphertext is not decrypted.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Frame ¶
type Frame struct {
HexInput string `json:"hex_input"`
FrameType string `json:"frame_type"`
LengthField *int `json:"length_field,omitempty"`
CField *int `json:"c_field,omitempty"`
CFieldName string `json:"c_field_name,omitempty"`
Direction string `json:"direction,omitempty"`
AField *int `json:"a_field,omitempty"`
AddressType string `json:"address_type,omitempty"`
CIField *int `json:"ci_field,omitempty"`
CIFieldName string `json:"ci_field_name,omitempty"`
Header *VDSHeader `json:"variable_data_header,omitempty"`
DataRecordsHex string `json:"data_records_hex,omitempty"`
ChecksumValid *bool `json:"checksum_valid,omitempty"`
Notes []string `json:"notes,omitempty"`
}
Frame is the decoded view of an M-Bus telegram.
func DecodeBytes ¶
DecodeBytes parses a raw M-Bus telegram.
type VDSHeader ¶
type VDSHeader struct {
HeaderType string `json:"header_type"`
SerialNumber string `json:"serial_number,omitempty"`
Manufacturer string `json:"manufacturer,omitempty"`
ManufacturerID *int `json:"manufacturer_id,omitempty"`
Version *int `json:"version,omitempty"`
Medium *int `json:"medium,omitempty"`
MediumName string `json:"medium_name,omitempty"`
AccessNumber int `json:"access_number"`
Status int `json:"status"`
SignatureHex string `json:"signature_hex,omitempty"`
}
VDSHeader is the fixed header of a Variable Data Structure response (the part before the DIF/VIF data records).
Source Files