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  3. B21 / B23 / B24

Janitza B21 / B23 / B24 Modbus register map

  • Official
  • 53 registers
  • Revision 3 · 2026-11-10

Official: Written from the manufacturer's documentation, but not tested on a device yet. Check the map against the manufacturer's documentation before you write to a live device. Tested it? Report a test.

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Communication

Protocol
Modbus TCP and RTUdefault
Unit ID
1default
TCP port
502default
Serial
9600 8E1 · 9600 baud, 8 data bits, even parity, 1 stop bit defaults
Byte / word order
ABCD · bytes big-endian, words high first
Addresses
0-based

Connection values are defaults: the device may be configured differently.

Map

Registers
53 holding registers
Revision
3 · 2026-11-10
Added
()
File
maps/janitza/b21-b23-b24.mbmap.json · 8 KB · history
SHA-256
ffec6e27aeb617ce76dd8c1a3f65197907a91d4f35bf76501812eaacb5bafb23
Manufacturer
janitza.com

Sources and notes

Source: Janitza electronics, "MID-Energiezähler Produkthandbuch", version 2.5, Doc. no. 2.100.005.2

  • Addresses are the protocol addresses of the manual; values are 32-bit floats read with FC03.
  • Not in this map: the special registers of chapter 4.4 (64-bit energy counters, tariffs, per-phase energy, integer measurements, inputs and outputs, identification); this map covers the UMG-compatible standard block.
  • Quantities that a given meter does not measure read as invalid values; the single-phase B21 has no per-phase L2 and L3 values.
AreaAddressNameTypeAccessUnitScaleDescription
HR 19000 float32 ABCD R V
HR 19002 float32 ABCD R V
HR 19004 float32 ABCD R V
HR 19006 float32 ABCD R V
HR 19008 float32 ABCD R V
HR 19010 float32 ABCD R V
HR 19012 float32 ABCD R A
HR 19014 float32 ABCD R A
HR 19016 float32 ABCD R A
HR 19020 float32 ABCD R W
HR 19022 float32 ABCD R W
HR 19024 float32 ABCD R W
HR 19026 float32 ABCD R W
HR 19028 float32 ABCD R VA
HR 19030 float32 ABCD R VA
HR 19032 float32 ABCD R VA
HR 19034 float32 ABCD R VA
HR 19036 float32 ABCD R var
HR 19038 float32 ABCD R var
HR 19040 float32 ABCD R var
HR 19042 float32 ABCD R var
HR 19044 float32 ABCD R
HR 19046 float32 ABCD R
HR 19048 float32 ABCD R
HR 19050 float32 ABCD R Hz
HR 19054 float32 ABCD R Wh
HR 19056 float32 ABCD R Wh
HR 19058 float32 ABCD R Wh
HR 19060 float32 ABCD R Wh
HR 19062 float32 ABCD R Wh
HR 19064 float32 ABCD R Wh
HR 19066 float32 ABCD R Wh
HR 19068 float32 ABCD R Wh
HR 19070 float32 ABCD R Wh
HR 19072 float32 ABCD R Wh
HR 19074 float32 ABCD R Wh
HR 19076 float32 ABCD R Wh
HR 19078 float32 ABCD R VAh
HR 19080 float32 ABCD R VAh
HR 19082 float32 ABCD R VAh
HR 19084 float32 ABCD R VAh
HR 19086 float32 ABCD R varh
HR 19088 float32 ABCD R varh
HR 19090 float32 ABCD R varh
HR 19092 float32 ABCD R varh
HR 19094 float32 ABCD R varh
HR 19096 float32 ABCD R varh
HR 19098 float32 ABCD R varh
HR 19100 float32 ABCD R varh
HR 19102 float32 ABCD R varh
HR 19104 float32 ABCD R varh
HR 19106 float32 ABCD R varh
HR 19108 float32 ABCD R varh

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