MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) Modbus register map

Updated 28 October 2026

Short answer

These MENNEKES home wallboxes become a Modbus RTU slave ('satellite') on RS-485 when DIP switches S1-4 and S1-5 are on, so an energy manager can control them. Data can be read as holding or input registers. This map covers identity, EVSE and CP state, configured current limits, per-phase current, voltage and power, session and lifetime energy, error codes and the control registers: heartbeat, charging release, current limit, phase switching and lock.

This page lists 51 Modbus registers for the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) — 7 writable — with the table, 0-based wire address, data type, word order, scale, units and access of each, re-typed from MENNEKES’s own free documentation (linked below) and checked against it.

Manufacturer: MENNEKES
Model: AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU)
Equipment type: EV charger
Registers: 51 (7 writable)
Transport: Modbus RTU
Default unit ID: 50
Default serial: 57600 baud, 8N2
Documented addressing: hexadecimal, 0-based
32-bit word order: ABCD high word first (big-endian)
Firmware: Software 2023.21.11024 and later (Modbus register layout v01.03)
Also known as: AMTRON 4You 300, AMTRON 4You 310, AMTRON Compact 2.0s, AMTRON Start 2.0s
Source document: Modbus RTU Specification - AMTRON 4You 300, AMTRON Compact 2.0s, AMTRON Start 2.0s · v2.5 · rev. 2025-07-11

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Integration notes: MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU)

Integration in brief

Every 10 s or faster, write 0x55AA to 0x0D00 (heartbeat); write 1 to 0x0D05 (release) and the current limit as a float to 0x0302 with function 16. Read 0x0100 (EVSE state), 0x0E00 (error), 0x0512 (power) and 0x0B02 (session energy).

Minimum registers to map

Addresses are 0-based wire addresses. Enough to monitor and run the unit; map more as the job needs.

Register	Name	Type	Why	Access
HR 3328	Heartbeat energy manager	UINT16	Heartbeat from the energy manager	Write
HR 3333	Charging release energy manager	UINT16	Charging release	Read/write
HR 770	Charging current energy manager	FLOAT32 ABCD	Charging current limit	Read/write
HR 256	EVSE state	UINT16	EVSE state	Read
HR 3584	Active error code	UINT16	Active error code	Read
HR 1298	Power overall	FLOAT32 ABCD	Total charging power	Read
HR 2818	Charged energy session	FLOAT32 ABCD	Session energy	Read
HR 3332	Requested phases	UINT16	1- or 3-phase request	Read/write

Enable Modbus control & writes

Set DIP switches S1-4 and S1-5 to ON and reboot; the wallbox then runs as a Modbus satellite at address 50 (10-50 can be set with the MENNEKES configuration tool).

Communication loss & watchdog

The energy manager must write 0x55AA to 0x0D00 at least every 10 s. What happens when it stops depends on 0x030E: 0 keeps charging with the last values received, 1 pauses charging, 6-32 charges at that fallback current. With no fallback active and no EV connected, the wallbox goes to error state (code 200 = energy manager not available); 0x0E01 shows when the fallback is active.

Byte order & addressing

0x0302 = 0 means unlimited, not stop; to pause, write a value between 0.01 and 5.99 A.
Floats and uint32 values need function 16 for writes; function 6 is only for single-register values.
Requested Phases (0x0D04) is ignored unless 0x030C reads 2 (phase-switch capable hardware, 11 kW models).

Network setup

RS-485: Modbus A = +, B = -.
Default 57600 baud, 8 data bits, no parity, 2 stop bits; other rates from 9600 to 57600 baud and 8E1 / 8O1 framing can be chosen with the MENNEKES configuration tool.

Watch out for

After a reboot or communication error the wallbox needs 0x0D00, 0x0D05 and 0x0302 written again before it returns to idle and charges.
MENNEKES recommends changing the current no faster than every 5 s and avoiding frequent pauses; some EVs (e.g. Fiat 500e) need the current set to 0 before a phase change.

MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) Modbus registers

Address = 0-based wire address (the documented number is shown under it when it differs) · Order: ABCD = high word first, CDAB = low word first · Scale: engineering value = raw × scale.

51 of 51 shown

MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) Modbus register map
Table	Address	Name	Description	Type	Order	Units	Access	Values / bits
HR	0doc 0x0000	Modbus version	Register layout version, e.g. 0x0103 = v01.03.	UINT16			Read
HR	1doc 0x0001	Firmware version	16 ASCII characters.	STRING[16]			Read
HR	19doc 0x0013	Serial number	16 ASCII characters (layout v01.02+).	STRING[16]			Read
HR	27doc 0x001B	MENNEKES article number	Article number from the type plate (layout v01.03+).	STRING[16]			Read
HR	256doc 0x0100	EVSE state		UINT16			Read	0 = Not initialized; 1 = Idle (no EV connected); 2 = EV connected (no current signalled); 3 = Preconditions valid, not charging yet; 4 = Ready to charge (current signalled); 5 = Charging; 6 = Error; 7 = Service mode
HR	257doc 0x0101	Authorization status	RFID / energy-manager release state.	UINT16			Read	0 = Not used (idle); 1 = Authorized (charging released); 2 = Not authorized
HR	258doc 0x0102	Downgrade	State of the external downgrade input.	UINT16			Read	0 = Not relevant (no EV); 1 = Not downgraded; 2 = Downgraded
HR	259doc 0x0103	Phase rotation	Configured phase order, used for load management.	UINT16			Read	0 = L1-L2-L3; 1 = L2-L3-L1; 2 = L3-L1-L2
HR	264doc 0x0108	CP state	Control-pilot state between wallbox and EV (layout v01.02+).	UINT16			Read	0 = Init; 10 = A1 (no EV); 11 = B1 (EV connected, not charging / paused); 12 = C1 (EV ready to charge); 13 = D1; 14 = E (error); 15 = F (error); 26 = A2 (current >= 6 A offered, EV disconnected); 27 = B2 (ready, current >= 6 A offered); 28 = C2 (charging, current >= 6 A offered); 29 = D2
HR	276doc 0x0114 - 0x0115	Signaled current	Current offered to the EV on the CP line (layout v01.03+).	FLOAT32	ABCD	A	Read
HR	768doc 0x0300 - 0x0301	Downgrade current	Current limit applied while the downgrade input is active.	FLOAT32	ABCD	A	Read
HR	770doc 0x0302 - 0x0303	Charging current energy manager	EMS current limit: 0 = no limit, 0.01-5.99 = pause, 6+ = limit.	FLOAT32	ABCD	A	Read/write
HR	772doc 0x0304 - 0x0305	Maximal current house (DIP)	Installation current set on DIP switches 6-8 of bank S2.	FLOAT32	ABCD	A	Read
HR	774doc 0x0306 - 0x0307	Maximal EVSE current	Maximum wallbox current set at installation.	FLOAT32	ABCD	A	Read
HR	778doc 0x030A	Phase switching mode	Phase use of the internal solar algorithm.	UINT16			Read	0 = Solar only 1 phase; 1 = Solar only 3 phases; 2 = Solar dynamic 1 or 3 phases
HR	780doc 0x030C	Phase options HW	Whether the hardware can switch between 1 and 3 phases.	UINT16			Read	0 = Only 1 phase; 1 = Only 3 phases; 2 = 1 or 3 phases (phase switch possible)
HR	781doc 0x030D	Cable lock setting	Permanent cable lock.	UINT16			Read	0 = Not enabled or unavailable; 1 = Enabled
HR	782doc 0x030E	Energy manager fallback current	Behaviour if the EMS heartbeat stops during a session; 6-32 = fallback amps.	UINT16			Read	0 = Fallback disabled, keep last EMS values; 1 = Fallback enabled, pause charging
HR	783doc 0x030F	Grid imbalance		UINT16			Read	0 = Disabled; 1 = Enabled
HR	784doc 0x0310	Grid imbalance threshold		UINT16		A	Read
HR	785doc 0x0311	Grid phases connected		UINT16			Read	0 = L1 connected; 2 = L1, L2, L3 connected
HR	786doc 0x0312	Authorization	Whether authorization is required.	UINT16			Read	0 = Disabled; 1 = Enabled
HR	787doc 0x0313	Sunshine+ minimum current	Minimum current in solar-supported (Sunshine+) mode.	UINT16		A	Read
HR	788doc 0x0314	Phase switching pause	Pause between a 1-to-3 or 3-to-1 phase switch.	UINT16		s	Read
HR	1280doc 0x0500 - 0x0501	Current L1	RMS output current.	FLOAT32	ABCD	A	Read
HR	1282doc 0x0502 - 0x0503	Current L2	RMS output current.	FLOAT32	ABCD	A	Read
HR	1284doc 0x0504 - 0x0505	Current L3	RMS output current.	FLOAT32	ABCD	A	Read
HR	1286doc 0x0506 - 0x0507	Voltage L1	RMS output voltage.	FLOAT32	ABCD	V	Read
HR	1288doc 0x0508 - 0x0509	Voltage L2	RMS output voltage.	FLOAT32	ABCD	V	Read
HR	1290doc 0x050A - 0x050B	Voltage L3	RMS output voltage.	FLOAT32	ABCD	V	Read
HR	1292doc 0x050C - 0x050D	Power L1		FLOAT32	ABCD	W	Read
HR	1294doc 0x050E - 0x050F	Power L2		FLOAT32	ABCD	W	Read
HR	1296doc 0x0510 - 0x0511	Power L3		FLOAT32	ABCD	W	Read
HR	1298doc 0x0512 - 0x0513	Power overall	Total power on all phases.	FLOAT32	ABCD	W	Read
HR	2304doc 0x0900 - 0x0901	Temperature	Temperature inside the wallbox.	FLOAT32	ABCD	°C	Read
HR	2816doc 0x0B00 - 0x0B01	Max current session	Highest current allowed for this session by static limits (cable, installation).	FLOAT32	ABCD	A	Read
HR	2818doc 0x0B02 - 0x0B03	Charged energy session	Energy delivered in the current session.	FLOAT32	ABCD	kWh	Read
HR	2820doc 0x0B04 - 0x0B05	Duration session	Length of the current session.	UINT32	ABCD	s	Read
HR	2822doc 0x0B06	Detected EV phases	Most phases the EV drew during this session.	UINT16			Read	0 = Not initialized; 1 = 1 phase; 2 = 2 phases; 3 = 3 phases
HR	3328doc 0x0D00	Heartbeat energy manager	EMS must write 0x55AA (21930) at least every 10 s.	UINT16			Write
HR	3330doc 0x0D02	Cable lock status		UINT16			Read	0 = Unknown; 1 = Cable unlocked; 2 = Cable locked; 3 = Fixed cable
HR	3331doc 0x0D03	Solar charging mode	Mode shown on the solar LEDs; also changed by the wallbox button.	UINT16			Read/write	0 = Solar mode not active; 1 = Fast charging (standard); 2 = Solar charging (Sunshine); 3 = Solar supported charging (Sunshine+)
HR	3332doc 0x0D04	Requested phases	Ask for 1-phase charging on phase-switch capable hardware.	UINT16			Read/write	0 = Charge on all available phases; 1 = Force 1-phase charging
HR	3333doc 0x0D05	Charging release energy manager	EMS release; 0 opens the relays.	UINT16			Read/write	0 = Charging not allowed; 1 = Charging allowed
HR	3334doc 0x0D06	Lock EVSE	Block charging at the wallbox.	UINT16			Read/write	0 = Not locked; 1 = Locked
HR	3353doc 0x0D19	System restart	Write 0xBB (187) once, only while idle (layout v01.03+).	UINT16			Write
HR	3584doc 0x0E00	Active error code	0 = no error.	UINT16			Read	0 = No error; 200 = Energy manager not available (no heartbeat); 2011 = EV overcurrent; 2323 = Connected phases mismatch
HR	3585doc 0x0E01	Master lost fallback state		UINT16			Read	0 = Not active; 1 = Active (energy manager unavailable)
HR	3586doc 0x0E02	Switched phases	Phases that will be used once the relays close.	UINT16			Read	0 = All available phases; 1 = 1 phase only
HR	4096doc 0x1000 - 0x1001	Charged energy total	Lifetime energy on the AC port; not for billing.	FLOAT32	ABCD	kWh	Read
HR	4098doc 0x1002 - 0x1003	Charging sessions total		UINT32	ABCD		Read

Notes on this map

The specification states 'Byte and Word Order: Big Endian', so float32 and uint32 values have the high word first (ABCD). Float values are in engineering units with no scaling.
Each register lists the register-layout version that introduced it (v01.00-v01.03); registers added in a later layout may be missing on older firmware (0x0114, 0x0D19 and 0x001B arrived with v01.03).
Charging current energy manager (0x0302): 0 means no limit and the wallbox signals its maximum (16 or 32 A); 0.01-5.99 A pauses charging; 6 A and up is a limit, clipped to the wallbox's own maximum.
Error codes 2300-2305 (over/undervoltage on L1-L3, with voltage detection active) are also listed in the source alongside the codes given under values.
Function codes per the source: read 0x03 or 0x04; write single register 0x06 only for 1-register values, write multiple 0x10 for floats (e.g. 0x0302).

Check it against the live device. A register map tells you what the controller can expose; the unit in front of you may differ by firmware or options. Read a few registers and compare them with the unit’s own display; for a 32-bit value the float and byte-order decoder shows all four word orders at once, so a wrong word order or scale is obvious. New to this? Read what a register map is and why addresses are off by one.

Questions about the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU)

What Modbus registers does the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) have?

This map lists 51 registers: 51 holding registers. 7 of them can be written. Registers vary with firmware, options and configuration, so confirm against the device.

Are the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) Modbus addresses 0-based or 1-based?

The manufacturer's document numbers registers hexadecimal, 0-based. Every address on this page is the 0-based wire address you put in the request; the documented number is shown under it where it differs. Addresses are printed in hex and go on the wire unchanged. The specification gives no example frame, but its table starts at register 0x0000 (Modbus version), which cannot exist in 1-based numbering, so the printed numbers are protocol addresses. So 0x0302 is requested as 770 decimal.

What byte order does the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) use for 32-bit values?

Multi-register values in this map use ABCD (high word first (big-endian)). Set your client to this order for every 32/64-bit value in the table.

What are the minimum Modbus registers to integrate the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU)?

Start with HR 3328 Heartbeat energy manager (Heartbeat from the energy manager); HR 3333 Charging release energy manager (Charging release); HR 770 Charging current energy manager (Charging current limit); HR 256 EVSE state (EVSE state); HR 3584 Active error code (Active error code); HR 1298 Power overall (Total charging power); HR 2818 Charged energy session (Session energy); HR 3332 Requested phases (1- or 3-phase request).

How do I enable Modbus control of the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU)?

Set DIP switches S1-4 and S1-5 to ON and reboot; the wallbox then runs as a Modbus satellite at address 50 (10-50 can be set with the MENNEKES configuration tool).

What happens when the MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) loses Modbus communication?

Where is the official MENNEKES AMTRON 4You 300 / Compact 2.0s / Start 2.0s (Modbus RTU) Modbus documentation?

The source is Modbus RTU Specification - AMTRON 4You 300, AMTRON Compact 2.0s, AMTRON Start 2.0s (v2.5), revision 2025-07-11, published free by MENNEKES at https://www.mennekes.de/fileadmin/MEN-Deutschland/emobility/01_documents/04_installer/Modbus_RTU_Specification_AMTRON_4You300_Compact_2.0s_Start_2.0s-v2.5.pdf.

Source: Modbus RTU Specification - AMTRON 4You 300, AMTRON Compact 2.0s, AMTRON Start 2.0s · v2.5 · rev. 2025-07-11. Register numbers, types, scaling and units are reproduced as published; descriptions are our own.