Systemair SAVE/SAVECair ventilation unit

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

point	address (0-based)	type	scale	unit
reg_demc_rh_highest	1000	U16	1
reg_demc_co2_highest	1001	U16	1
reg_demc_fan_speed	1002	U16	1
reg_demc_active_controller	1003	U16	1
reg_summer_winter	1038	U16	1
reg_iaq_level	1122	U16	1
reg_usermode_mode	1160	U16	1
reg_speed_manual_saf	1200	U16	1
reg_speed_manual_eaf	1201	U16	1
reg_speed_auto_saf	1202	U16	1
reg_speed_auto_eaf	1203	U16	1
reg_saf_stopped	1354	U16	1
reg_eaf_stopped	1355	U16	1
reg_tc_sp	2000	U16	0.1
reg_tc_cascade_sp	2012	U16	0.1
reg_heat_exchanger_from_satc	2140	U16	1
reg_rotor_ea_spec_humidity	2210	U16	1
reg_rotor_oa_spec_humidity	2211	U16	1
reg_sensor_fpt	12100	I16	0.1
reg_sensor_oat	12101	I16	0.1
reg_sensor_sat	12102	I16	0.1
reg_sensor_rat	12103	I16	0.1
reg_sensor_eat	12104	I16	0.1
reg_sensor_ect	12105	I16	0.1
reg_sensor_eft	12106	I16	0.1
reg_sensor_oht	12107	I16	0.1
reg_sensor_rhs	12108	U16	1
reg_sensor_co2s	12114	U16	1
reg_sensor_p_saf	12200	U16	1
reg_sensor_p_eaf	12201	U16	1
reg_sensor_flow_saf	12202	U16	1
reg_sensor_flow_eaf	12203	U16	1
reg_sensor_rpm_saf	12400	U16	1	rpm
reg_sensor_rpm_eaf	12401	U16	1	rpm
reg_sensor_pdm_eat_value	12543	U16	0.1
reg_output_saf	14000	U16	1
reg_output_eaf	14001	U16	1
reg_output_alarm	14002	U16	1
reg_output_y1_analog	14100	U16	1

link settings as documented (unverified): MODBUS is a serial communication protocol used for transmitting information over serial lines between electronic devices. The device requesting the information is called the Master and the devices supplying information are Slaves.

bench facts as documented (unverified)

doc revision

vA001

field reports — community-sourced, unverified (checked 2026-06-11)

Modbus addresses in standard Systemair SAVE documentation have an offset of -1 compared to the actual register addresses because the manual specifies 1-based register numbers while many Modbus clients use 0-based addressing. [source]
The extract air temperature register (REG_SENSOR_EAT) always returns 0 on some units. [source]
In some firmware versions, the register order for overheat temperature and humidity was swapped. [source]
If using a Regin E-CABLE2-USB converter, the yellow and orange wires must be swapped (yellow to B(-) and orange to A(+)). [source]
Modbus integration can experience instability or crashes, stopping data retrieval until a reboot of the Home Assistant host or Modbus gateway is performed. [source]
confirmed: reg_demc_rh_highest @ 1000 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_demc_co2_highest @ 1001 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_demc_fan_speed @ 1002 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_demc_active_controller @ 1003 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_summer_winter @ 1038 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_iaq_level @ 1122 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_usermode_mode @ 1160 — confirmed by SAVECair Modbus variable list vA001
confirmed: reg_speed_manual_saf @ 1200 — confirmed by SAVECair Modbus variable list vA001

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.
coherence-checked — Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

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