The Delta AC MAX Smart is a Mode 3 AC wallbox for electric vehicle charging, available in 7 kW (single-phase), 11 kW and 22 kW (three-phase) variants. It communicates with TapHome via Modbus TCP over Ethernet on port 502 — no RS-485 wiring is required (unlike the AC MAX Basic which uses Modbus RTU).

The template provides charger and EVSE status monitoring, real-time power metering, and a writable register for charging power limit control. The AC MAX Smart supports a single EVSE connector with offset-based addressing (EVSE 1 = base register + 1000).

The AC MAX Smart shares the same Modbus register document as the Basic variant, but several EVSE-level registers (A:1001, A:1003, A:1007, A:1017, A:1019, A:1047) have been reported as non-functional on the Smart variant by the evcc community. These registers are included in the template and may work with newer firmware versions.

Hardware connection

The AC MAX Smart connects via Ethernet (RJ45). The Ethernet port is located behind a waterproof cap on the bottom of the unit.

1. Remove the waterproof cap
2. Pass the Ethernet cable through an appropriate conduit or cable gland
3. Connect the RJ45 cable to the Ethernet port
4. Secure the cable gland

Use a Category 5 (Cat 5) or better Ethernet cable. Connect the charger to the same local network as TapHome Core.

Mains wiring

The terminal block inside the unit accepts L1, L2, L3, N and PE conductors. Use 10 mm² copper wire with cord end terminals (DIN 46228-4).

Wiring diagrams by grounding system

The charger supports TT, TN-C, TN-S, TN-C-S, and IT grounding systems in both single-phase and three-phase configurations.

• Single phase: L1, N, PE
• Three phase: L1, L2, L3, N, PE (or L1, L2, L3, PE for IT system)

For UK installations on TN-C-S systems, the charger needs a separate ground to a TT system. PME earthing shall not be used for outdoor charging points.

Configuration

DIP switch settings

Six DIP switches on the control board configure charger behavior. Access requires removing the front and middle covers (Torx T20/T30).

Maximum current settings (Pins 4/5/6):

* Depends on model configuration. For 16 A models, settings above 16 A fall back to 6 A.

Set the maximum current DIP switches before commissioning. Some vehicles do not initiate a charging session at 6 A (the default).

Enabling Modbus communication

The AC MAX Smart has Modbus TCP enabled by default on port 502. No special configuration is required to activate Modbus communication.

The charger must be set to “Local operation” mode (not OCPP-managed) for external Modbus control to work. This is configured via the Web Configuration Tool.

Web Configuration Tool

Access the charger configuration interface:

Via Ethernet:

1. Configure laptop IP: 192.168.123.101, Subnet: 255.255.255.0
2. Open browser, navigate to 192.168.123.123

Via WiFi:

1. Connect to SSID: Delta-{serial_number}
2. Password: see Quick Installation Guide
3. Open browser, navigate to 192.168.5.1

Login: User: admin, Password: see Quick Installation Guide. After 5 failed attempts the account is locked for 5 minutes.

When importing the template in TapHome, provide:

• IP Address — the charger’s IP on the local network
• Slave ID — Modbus slave address (default: 1)

Assign a static IP address or DHCP reservation for the charger in the router settings to prevent the address from changing after a power cycle. The charger does not support mDNS discovery.

Device capabilities

Charger and EVSE status

The template provides three status indicators:

• Charger State — overall charger condition read from register A:100: Not ready (0), Operational (1), or Faulted (2)
• EVSE Condition — OCPP-based EVSE status read from register A:1000 with 10 states: Unavailable, Available, Occupied, Preparing, Charging, Finishing, Suspended EV, Suspended EVSE, Not ready, Faulted. This is the primary status register confirmed working on the Smart variant.
• Charge State — charging process state read from register A:1001 with states from “not started” through “charging” to “completed” or “error”. Community reports indicate this register may return “illegal data address” on the Smart variant — use EVSE Condition instead.

Power and energy metering

Real-time electrical measurements from the EVSE:

• Charging Power — instantaneous charging power in watts (A:1005). Confirmed working on the Smart variant, though some firmware versions may have UINT32 format discrepancies.
• Output Voltage — charging voltage in volts (A:1003, scaled /10)
• Output Current — charging current in amps (A:1007, scaled /100)
• Charged Energy — energy transferred to the EV during the current session in Wh (A:1019)
• Total Power Consumption — total power consumption at the grid connection in watts (A:1047)
• Charging Time — duration of the current charging session in minutes (A:1017, converted from seconds /60)

Community testing indicates that registers A:1003, A:1007, A:1017, A:1019, and A:1047 may return zero values on some Smart firmware versions. These registers are included in the template and may work with newer firmware. The Charging Power register (A:1005) and EVSE Condition (A:1000) are confirmed working.

Charging control

• Charging Power Limit (H:1600) — sets the maximum charging power in watts. Writing 0xFFFFFFFF removes the limit (displayed as no value). Reading is confirmed working on the Smart variant. Writing may not take effect on all firmware versions.

Additional capabilities

The AC MAX Smart also exposes registers for per-phase grid power consumption (L1, L2, L3), per-phase EVSE current, max/min charging power determined by EVSE, IEC 62196 plug state, and RFID authentication ID. Communication timeout registers (H:201-203) allow configuring a safety fallback power level if no Charging Power Limit command is received within a specified interval. The Suspend Charging register (H:1602) present in the Basic variant template is not included in the Smart template but may be available. These can be added in a future template update.

The communication timeout feature (registers H:201-203) is useful for safety: if TapHome loses communication with the charger, a preconfigured fallback power level is applied automatically. This can be configured directly via Modbus writes to H:201 (enable), H:202 (timeout in seconds, 0-600) and H:203 (fallback power in watts).

Troubleshooting

No Modbus communication

1. Verify the Ethernet cable is connected to the RJ45 port (not the USB port)
2. Confirm the charger is set to “Local operation” mode (not OCPP-managed)
3. Ensure TapHome Core and the charger are on the same network/subnet
4. Check that Modbus TCP port 502 is not blocked by a firewall
5. Try accessing the Web Configuration Tool (192.168.123.123 via Ethernet) to verify the charger is reachable

Register read errors (illegal data address)

Some EVSE registers (particularly A:1001 Charge State) return “illegal data address” on the Smart variant. This is a known limitation. Use the EVSE Condition register (A:1000) for status monitoring instead.

Charging Power reads incorrect values

The Charging Power register (A:1005) may show UINT32 format discrepancies on some firmware versions. If the value appears incorrect, check the firmware version via the Web Configuration Tool and update if a newer version is available.

Charging Power Limit has no effect

Writing to H:1600 has been reported as ineffective on some firmware versions. Ensure the charger firmware is up to date. Firmware updates can be uploaded via the Web Configuration Tool.

LED indicator reference