Heidelberg Connect
The Heidelberg Connect is an AC wallbox for electric vehicle charging, designed for residential and commercial installations with built-in dynamic load management. This ModbusCloud template connects over Modbus TCP and reads per-phase voltage and current on L1, L2, and L3, active power, PCB temperature, external lock state, and cumulative energy counters. Writable registers let your system command the charging current setpoint, toggle a remote lock, configure the watchdog timeout and failsafe current, and switch between single-phase and three-phase operation. The result is full remote visibility and control of every Heidelberg Connect charger in your portal.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 25, read and write
- Brand
- Heidelberg
- Last updated
Registers (25)
20 read, 5 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| layout_version | Read | ||||
| charging_state | Read | ||||
| current_l1 | A | Read | |||
| current_l2 | A | Read | |||
| current_l3 | A | Read | |||
| temperature_pcb | °C | Read | |||
| voltage_l1 | V | Read | |||
| voltage_l2 | V | Read | |||
| voltage_l3 | V | Read | |||
| extern_lock_state | Read | ||||
| active_power | W | Read | |||
| active_production_energy | Wh | Read | |||
| heidelberg_energy_session | Wh | Read | |||
| raw_maximal_current | A | Read | |||
| raw_minimal_current | A | Read | |||
| watchdog_timeout_a | s | Read | |||
| watchdog_timeout_b | s | Write | |||
| remote_lock_a | Read | ||||
| remote_lock_b | Write | ||||
| set_charging_current_a | A | Read | |||
| set_charging_current_b | A | Write | |||
| failsafe_current_a | A | Read | |||
| failsafe_current_b | A | Write | |||
| phase_switch_control_a | Read | ||||
| phase_switch_control_b | Write |
Loading registers…
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Use cases
- Monitor per-phase current and voltage on L1, L2, and L3 to detect imbalanced loads across your site.
- Track cumulative energy delivered per wallbox to allocate charging costs across tenants or fleet drivers.
- Alert on PCB temperature readings above a threshold to catch ventilation or mounting problems early.
- Compare active power against the charging current setpoint to verify the wallbox is responding to Modbus commands.
- Report session energy per charge cycle to validate billing data against vehicle onboard counters.
Installation
Enable Modbus TCP on the Heidelberg Connect: confirm the wallbox has an active network connection, then verify TCP port 502 is reachable from the ModbusCloud Gateway on the same LAN segment.
Connect the ModbusCloud Gateway to the same network as the wallbox, assign the wallbox a static IP address via your router or switch, and note the unit ID configured via the wallbox DIP switches.
In the ModbusCloud portal, add a new gateway, import the Heidelberg Connect template, and enter the wallbox IP address, port 502, and the correct Modbus unit ID.
Spot-check the connection by reading register 5 (charging_state) and register 10 (voltage_l1); a voltage value near 230 V and a valid charging state confirm communication is working.
Things to watch for
The gateway connects but all register values are zero or absent.
The Heidelberg Connect enters standby when no vehicle is plugged in, and Modbus communication is suspended in that state. Plug in a vehicle or check whether the standby function is active. Once a vehicle connects, the wallbox wakes and register reads will return valid values.
Charging current setpoint writes to register 261 have no effect.
Register 261 resets to 0 after a power cycle or standby exit on some firmware versions, which the wallbox interprets as a Modbus fault. Write a valid current value (within the min/max current limits) immediately after reconnection. Also confirm the remote lock register 259 is set to 1 (unlocked) and the external lock input is not asserting a hardware lock.
The wallbox blinks an error LED during Modbus polling. What is wrong?
The built-in watchdog is enabled by default. If your controller does not refresh the watchdog within the configured timeout interval in register 257, the wallbox enters timeout mode and signals a fault. Either send regular Modbus traffic within the timeout window or write 0 to register 257 to disable the watchdog during initial setup. ModbusCloud polls at most once per minute, every 5 minutes by default, so a timeout shorter than your polling interval will trip. In that case, write 0 to register 257.
Is it safe to write charging current or phase switch commands remotely?
Yes, but take care: writing a current value outside the hardware-configured min/max range (readable from registers 100 and 101) will be rejected or clamped by the wallbox. Setting the failsafe current register 262 to an inappropriate value means the vehicle may charge at an unintended rate if Modbus communication is interrupted. Always set a safe, non-zero failsafe current before enabling remote current control.
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