Bitzer LMC340i condensing controller

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire; word order and scaling are only confirmed at the hardware-verified rung.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale	unit
second_setpoint_active	1537	U16	1
low_sound_fan_mode_active	1538	U16	1
winter_start_enabled	1539	U16	1
heat_recovery_enabled	1540	U16	1
setpoint_source	1541	U16	1
status_icon	1542	U16	1
min_run_active	1543	U16	1
min_pause_active	1544	U16	1
lim_tc_active	1545	U16	1
lim_tdis_active	1546	U16	1
lim_tfi_active	1547	U16	1
lim_dp_active	1548	U16	1
lim_psuc_active	1549	U16	1
lim_ifi_active	1550	U16	1
saturated_suction_temperature	1552	I16	0.01	°C
room_temperature	1553	I16	0.01	°C
saturated_discharge_temperature	1554	I16	0.01	°C
discharge_temperature	1555	I16	0.01	°C
ambient_temperature	1556	I16	0.01	°C
suction_temperature	1557	I16	0.01	°C
suction_superheat_temperature	1558	I16	0.01	°C
discharge_superheat_temperature	1559	I16	0.01	°C
frequency_inverter_temperature	1560	I16	0.01	°C
frequency_inverter_current	1561	I16	0.01	A
external_input_offset	1562	I16	0.01
suction_pressure	1563	I16	0.01	bar
discharge_pressure	1564	I16	0.01	bar
high_pressure_switch_input	1565	U16	1
oil_level_failure	1566	U16	1
compressor_overheated	1567	U16	1
fan1_overheated	1568	U16	1
fan2_overheated	1569	U16	1
digital_input_1	1570	U16	1
digital_input_2	1571	U16	1
external_release_input	1572	U16	1
security_chain_compressor_1	1573	U16	1
security_chain_compressor_2	1574	U16	1
relay_output_re1	1584	U16	1
relay_output_re2	1585	U16	1
relay_output_re3	1586	U16	1
relay_output_re4	1587	U16	1
relay_output_re5	1588	U16	1
relay_output_re6	1589	U16	1
relay_output_re7	1590	U16	1
relay_output_re8	1591	U16	1
relay_output_re9	1592	U16	1
alarm_count	1600	U16	1
active_alarm_count	1601	U16	1
highest_alarm_level	1602	U16	1
alarm_reset	1603	U16	1
alarm_code_1	1604	U16	1
overall_unit_mode	1632	U16	1
temperature_control_mode	1633	U16	1
runtime_hours	1634	U16	1
mb_external_on_off	1635	U16	1
condenser_tc_setpoint	1636	I16	0.01	°C
fan_control_mode	1637	U16	1
ambient_compensation	1638	U16	1
capacity_controller_setpoint	1639	I16	0.01	°C
secondary_setpoint	1640	I16	0.01	°C
actual_setpoint	1641	I16	0.01	°C
capacity_request	1642	I16	0.01	%
actual_capacity	1643	I16	0.01	%
actual_fi_frequency	1644	I16	0.01	Hz
compressor_running	1645	U16	1

link settings as documented (unverified): RTU; default 115200 8E1; unit ID 1; FC 03,04,06,23; Settings are configured on the LUP200 display of the LMC340i controller in the Service->LOM MB config menu. Parity can be Even, None, or Odd. Stop bits default to 1, but is 2 if Parity is None.

bench facts as documented (unverified)

terminals	CN32 - RS485
A/B polarity	Data- Inverted signal, Data+ Signal
termination	2 * 120Ω termination
connector	CN32
shield/ground	grounded shield
wiring notes	Max. 100m twisted pair cable, shunt capacitance < 50pF/m, 100Ω resistance, AWG24. Receiver impedance >= 12kΩ.
max registers/read	32
protocol notes	Communication is half duplex. Register numbers used in this manual are zero-based as the LMC340i uses PDU telegrams.
power	range 15 - 30 VDC/12 – 24 VAC
certifications	CE approved, RoHS 2002/95/EC, Low voltage 206/95/EC, EMC 2004/108/EC, 61000-6-x Generic EMC, EN 61010-1, EN 61000-6-2, EN 61000-6-3
doc revision	Ver. 1.0 - 25.10.13

generated by gemini:gemini-3.5-flash · harvested from http://cis.bitzer.ru/files/File/IQ-Products/LMC340i%20Modbusmanual%20Ver%201.0_high.pdf (Bitzer); manual-faithful — the document's claims, panel risk: LOW — panel concurs, no field disagreements; proved interop-verified on 2026-06-10 · recorded 2026-06-10

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

Have a device that isn't here? Upload its register map — generation is free, and the connector earns its rung by being proven, not claimed.

Need it proven on your own device? Hardware verification — if it doesn't verify, you don't pay.

Building a platform? License the verified library — machine-readable maps, firmware matrix, API access.