Systemair Topvex SX/TX/SR/TR air handling 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.

structure-verified

Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.

point	address (0-based)	type	scale	unit
Vpac1.TimeExtension	1	U16	1
TimePro.TimeGroupUnit	1	U16	1
Vpac1. UnitType	1	U16	1
StdObjs1.Ai1_SupplyTemp_Output	1	I16	10
Vpac1.FilterAlarmReset	2	U16	1
QDig.DI1	2	U16	1
Vpac1.Unitmode	2	U16	1
StdObjs1.Ai2_ExhaustAirTemp_Output	2	I16	10
StdObjs1.FireAlarmActive	3	U16	1
QDig.DI2	3	U16	1
Vpac1.Regulation	3	U16	1
StdObjs1.Ai3_FrostProtectionTemp_Output	3	I16	10
StdObjs1.AktiveFanFire	4	U16	1
QDig.DI3	4	U16	1
Vpac1.UnitOffLow	4	U16	1
StdObjs1.Ai4_OutDoorTemp_Output	4	I16	10
Vpac1.NightCool_Enable	5	U16	1
QDig.DI4	5	U16	1
Vpac1.FanSpeedChoice	5	U16	1
QAnaIn.AI1	5	I16	10
QDig.DI5	6	U16	1
Vpac1.FilterAlarmModBus	6	U16	1
QAnaIn.AI2	6	I16	10
QDig.DQ1	7	U16	1
Vpac1.SupplyTempModBus	7	U16	1	°C
QAnaIn.AI3	7	I16	10
QDig.DQ2	8	U16	1
Vpac1.Cooling	8	U16	1
QAnaIn.AI4	8	I16	10
QDig.DQ3	9	U16	1
Vpac1.CoolRecycling	9	U16	1
StdObjs1.Ao1_Heating_OutPut	9	I16	10
QDig.DQ4	10	U16	1
Vpac1.HeatBatteryType	10	U16	1
StdObjs1.Ao2_Cooling_OutPut	10	I16	10
QDig.DQ5	11	U16	1
StdObjs1.Do4_Exchanger_Select	11	U16	1
StdObjs1.Ao3_RotatingSpeed_OutPut	11	I16	10	%
StdObjs1.Ao1_Heating_Select	12	U16	1
QAnaOut.AQ1	12	I16	10	V
StdObjs1.Ao2_Cooling_Select	13	U16	1
QAnaOut.AQ2	13	I16	10	V
StdObjs1. Ao3_RotatingSpeed_Select	14	U16	1
QAnaOut.AQ3	14	I16	10	V
Vpac1.Ao1_ManInput	15	I16	10	V
QAnaOut.AQ4	15	I16	10	V
Vpac1.Ao2_ManInput	16	I16	10	V
QAnaOut.AQ5	16	I16	10	V
Vpac1.Ao3_ManInput	17	I16	10	V
Vpac1.FanSpeed_HighsetP	18	I16	1	%
Vpac1.FanSpeed_MediumSetP	19	I16	1	%
Vpac1.FanSpeed_LowsetP	20	I16	1	%
Vpac1.SetPoint_M20	21	I16	1
Vpac1.SetPoint_M15	22	I16	1
Vpac1.MinSupplyTemp	23	I16	1
Vpac1.MaxSupplyTemp	24	I16	1
Vpac1.Unit_Pgain	25	I16	1
Vpac1.Unit_Itime	26	I16	1
Vpac1.Unit_Cascade_PGain	27	I16	1
Vpac1.Unit_cascade_ITime	28	I16	1
Vpac1.TimeExtensionSetPoint	29	I16	1
Not used	30	I16	1
Vpac1.FanSpeedChoice_Forced	31	U16	1
Vpac1.NightCool_OutdoorDay	32	I16	1
Vpac1.NightCool_OutdoorHighNight	33	I16	1
Vpac1.NightCool_OutdoorLowNight	34	I16	1
Vpac1.NightCool_RoomLimit	35	I16	1
StdObjs1.Ao4_RotatingSpeedEAF_Select	36	U16	1
StdObjs1.Ao5_Bypass_Select	37	U16	1
AlaPts.FilterAlarm	50	U16	1
TimeDp.Posts(0).T1	50	I16	100	h
AlaData.FilterAlarm_Status	50	U16	1
AlaPts.AlarmFanMotor	51	U16	1
TimeDp.Posts(0).T2	51	I16	100	m
AlaData.AlarmFanMotor_Status	51	U16	1
AlaPts.Overheat	52	U16	1
TimeDp.Posts(0).T3	52	I16	100
AlaData.Overheat_Status	52	U16	1
AlaPts.ExchangerRotatingAlarm	53	U16	1
TimeDp.Posts(0).T4	53	I16	100
AlaData.ExchangerRotatingAlarm_Status	53	U16	1
AlaPts.AlarmFrostProt	54	U16	1
TimeDp.Posts(1).T1	54	I16	100
AlaData.AlarmFrostProt_Status	54	U16	1
AlaPts.FireAlarm	55	U16	1
TimeDp.Posts(1).T2	55	I16	100
AlaData.FireAlarm_Status	55	U16	1
Not used	56	U16	1
TimeDp.Posts(1).T3	56	I16	100
NOT USED	56	U16	1
AlaPts.SensorAlarm_SupplyTemp	57	U16	1
TimeDp.Posts(1).T4	57	I16	100
AlaData.SensorAlarm_SupplyTemp _Status	57	U16	1
AlaPts.SensorAlarm_ExhaustTemp	58	U16	1
TimeDp.Posts(2).T1	58	I16	100
AlaData.SensorAlarm_ExhaustTemp_Status	58	U16	1
AlaPts.SensorAlarm_FrostTemp	59	U16	1
TimeDp.Posts(2).T2	59	I16	100
AlaData.SensorAlarm_FrostTemp_Status	59	U16	1
AlaPts.SensorAlarm_OutDoorTemp	60	U16	1
TimeDp.Posts(2).T3	60	I16	100
AlaData.SensorAlarm_OutDoorTemp_Status	60	U16	1
AlaPts.InternalBatteryError	61	U16	1
TimeDp.Posts(2).T4	61	I16	100
AlaData.InternalBatteryError_Status	61	U16	1
TimeDp.Posts(3).T1	62	I16	100
TimeDp.Posts(3).T2	63	I16	100
TimeDp.Posts(3).T3	64	I16	100
TimeDp.Posts(3).T4	65	I16	100
TimeDp.Posts(4).T1	66	U16	0.01
TimeDp.Posts(4).T2	67	U16	0.01
TimeDp.Posts(4).T3	68	U16	0.01
TimeDp.Posts(4).T4	69	U16	0.01
TimeDp.Posts(5).T1	70	U16	0.01
TimeDp.Posts(5).T2	71	U16	0.01
TimeDp.Posts(5).T3	72	U16	0.01
TimeDp.Posts(5).T4	73	U16	0.01
TimeDp.Posts(6).T1	74	U16	0.01
TimeDp.Posts(6).T2	75	U16	0.01
TimeDp.Posts(6).T3	76	U16	0.01
TimeDp.Posts(6).T4	77	U16	0.01
Alarms.AlaAcknow	150	U16	1
Alarms.AlaBlock	151	U16	1
Alarms.AlaUnBlock	152	U16	1

link settings as documented (unverified): baud 9600; FC 01,02,03,04,05,06,15,16; The modbus master must wait for a minimum of 3.5 charactertimes (4ms at 9600 bps) between two messages. When the modbus master communicate with more than one controller on the same communication line (RS485), the modbus master must wait for a minimum of 14 charactertimes (16ms at 9600bps) between the answer and the first question for the next controller.

bench facts as documented (unverified)

wiring notes	RS485 communication line
max registers/read	47
inter-frame delay	4 ms
broadcast	not supported
protocol notes	In the controller there is a limit of 10 fast communications in every half minute, the other communications will have a delayed answer of approximately 1 second.
identification notes	The address of the controller is always as default PLA=254 and ELA=30.
doc revision	11-12-05 A002

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

confirmed: comms defaults (baud rate 9600, function codes 1, 2, 3, 4, 5, 6, 15, 16) — confirmed by Systemair Topvex Modbus Exoline Variables document (11-12-05 A002) [1.3.1]
confirmed: inter-frame delay and communication limits (3.5 charactertimes / 4ms at 9600 bps, 14 charactertimes / 16ms between controllers) — confirmed by Systemair Topvex Modbus Exoline Variables document (11-12-05 A002)
confirmed: default PLA=254 and ELA=30 — confirmed by Systemair Topvex Modbus Exoline Variables document (11-12-05 A002)
confirmed: limit of 10 fast communications per half minute (others delayed by ~1s) — confirmed by Systemair Topvex Modbus Exoline Variables document (11-12-05 A002)
confirmed: register map addresses (e.g., StdObjs1.Ai1_SupplyTemp_Output at address 1, Vpac1.UnitType at address 1, AlaData.FilterAlarm_Status at address 50) — confirmed by Systemair Topvex Modbus Exoline Variables document (11-12-05 A002)

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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