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IEC 62056-21 · (IEC 61107)

Meter sign-on, decoded end to end

Watch the optical/serial sign-on play out — request, identification, ACK and data — with the BCC verified, the baud change tracked, and a clean hand-over to DLMS when the meter switches to Mode E.

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Sign-on decoded

Request, identification, ACK and data blocks parsed — with the BCC checksum verified.

Modes A–E & baud

Recognises the mode and the baud-rate change negotiated during sign-on.

Drive it with quick-send

Send the sign-on and option-select via quick-send or a saved sequence.

Mode E → DLMS

Detects the hand-over to HDLC/DLMS automatically and keeps decoding.

Value parsing

The whole handshake, in plain view

The IEC sign-on is a precise little dance. Omni Console labels each step — and verifies the BCC — so you can see exactly where a stubborn meter stalls.

  • Request, identification (vendor + baud Z), ACK and data block
  • BCC checksum verified; OBIS-style readout values shown
  • Baud-rate negotiation tracked from 300 up to the selected rate
Omni Console — IEC 62056-21
IEC 62056-21 Mode C · 300→9600 baud
08:10:01.020  TX  2F 3F 21 0D 0A  /?!
→ request message (sign-on)
08:10:01.​​​  RX  2F 49 53 6B 35 ...  /ISk5\2MT382
→ identification · vendor ISk · baud 9600 (Z=5)
08:10:01.260  TX  06 30 35 31 0D 0A  ACK 0 5 1
→ ACK · select baud 9600 · data readout
08:10:02.640  RX  02 ... 21 0D 0A 03 7A  STX…!ETX BCC
→ data block · BCC ok · 1.8.0 = 48 213 kWh ▋
Modes A–E · BCC verified · Mode E hand-over to DLMS detected automatically

Speaks raw, too — not just the named protocols

Point Omni Console at any serial device and read the line in ten display modes — ASCII, HEX, Mixed, Decimal, Binary, Raw and Events — with full-text search and export. It also decodes the proprietary O1TP framing out of the box. Modbus, DLMS, M-Bus, IEC 62056-21 and MASS simply get the extra layer: deep value parsing that turns bytes into labelled, unit-aware readings — plus command builders for Modbus, M-Bus and DLMS.

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IEC 62056-21 questions

Sign-on, answered

Which IEC 62056-21 modes are supported?
Sign-on for Modes A–E is decoded: the request, the identification message (with the baud Z character), the ACK/option-select and the data readout, with the BCC verified.
Does it follow the baud-rate switch?
Yes. The identification advertises a baud rate and the ACK selects it; Omni Console tracks the negotiated change through the session.
What about Mode E (DLMS)?
When sign-on hands over to HDLC, Omni Console decodes the DLMS frames that follow — the seamless meter-readout path.
Can it act as the master?
Yes — send the sign-on and option-select via quick-send or a saved sequence to drive a meter through the readout, and watch each step decode. (There's no dedicated IEC frame builder; sending is via quick-send.)

Explore the other protocols

Modbus RTU · ASCII · TCP, register maps DLMS / COSEM HDLC, OBIS, AES-GCM, HLS M-Bus Self-describing DIF/VIF MASS Turkish metering standard

Tame meter sign-on.

Download Omni Console and decode an IEC 62056-21 readout — free for 30 days.

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