All registers return zero or connection fails immediately. Why?

Modbus TCP and the UDP interface share the same port and cannot run simultaneously on the P30. If the wallbox was previously controlled via UDP, DIP switch DSW1.3 must be set to ON and the station restarted before Modbus TCP will respond. Also confirm the unit ID in your portal configuration is exactly 255.

The active_power register reads in milliwatts, not watts. Is my scaling wrong?

The Keba P30 Modbus documentation states that register 1020 reports active power in milliwatts internally. The template maps this to the unit 'W' after dividing by 1000. If your portal shows raw register values without scaling, apply a divide-by-1000 factor to convert milliwatts to watts.

Writing to set_charging_current has no effect. What should I check?

The P30 only accepts current values between 6000 and 63000 (milliamps); values outside this range are silently ignored. Also verify that register 5014 (set_enable) is set to 1 to enable the station. The hardware-rated maximum from cable coding and DIP switches always takes precedence over the written setpoint.

Is it safe to write to set_enable or set_trigger_phase_switch during an active session?

Use write registers with care during active charging. Disabling the station via set_enable immediately stops an ongoing session. Triggering a phase switch mid-session can interrupt charging and, on some firmware versions, requires the charging process to be stopped beforehand. Unexpected writes may also invalidate manufacturer warranty coverage for damaged sessions. Always test write sequences in a controlled environment before deploying automation.

Free Modbus template: Keba Modbus

Name: Keba Modbus
Brand: Keba
SKU: 19a09969-fb6e-45fa-a12a-42ff27a757e0

The Keba KeContact P30 is a Mode 3 AC EV wallbox used in residential, commercial, and fleet charging installations. This Modbus template connects to the P30 c-series and x-series over Modbus TCP and reads charging state, cable state, active power, session energy, cumulative energy, power factor, and maximum current limits. Write registers let your energy management system set the charging current in milliamps, define a session energy limit, enable or disable the station, and trigger a 1-phase/3-phase switch. The template gives installers live charge supervision and dynamic load control directly inside the ModbusCloud portal.

Registers (21)

15 read / 6 write

Name	Address	Function	Type	Unit	Access
charging_state Current state of the charging station as an enumerated code.	1000	FC03	uint32		R
cable_state Cable connection status: unplugged, connected, locked, or charging.	1004	FC03	uint32		R
error_code Active EVSE error code; zero when no fault is present.	1006	FC03	uint32		R
serial_number Unique serial number of the charging station.	1014	FC03	uint32		R
firmware Firmware version; decimal value, convert to hex to read.	1018	FC03	uint32		R
active_power Instantaneous AC charging power in watts.	1020	FC03	uint32	W	R
active_production_energy Cumulative energy delivered since installation, in watt-hours.	1036	FC03	uint32	Wh	R
power_factor Power factor (cos phi) in 0.1% units; 1000 equals 100%.	1046	FC03	uint32	%	R
max_charging_current Current maximum charging current permitted by the station, in amperes.	1100	FC03	uint32	A	R
max_supported_current Hardware-rated maximum current from cable coding, in amperes.	1110	FC03	uint32	A	R
energy_session Energy transferred during the current charging session, in watt-hours.	1502	FC03	uint32	Wh	R
phase_switch_source Active communication channel controlling the phase switch (contact X2).	1550	FC03	uint32		R
phase_switch_state Current phase switching state: 1-phase or 3-phase operation.	1552	FC03	uint32		R
failsafe_current_setting Active failsafe charging current applied when Modbus communication is lost.	1600	FC03	uint32	A	R
failsafe_timeout_setting Active failsafe timeout in seconds before fallback current takes effect.	1602	FC03	uint32	s	R
set_charging_current Charging current setpoint in milliamps; accepted range 6000 to 63000.	5004	FC16	uint16	A	W
set_energy_limit Session energy limit setpoint; station stops charging when limit is reached.	5010	FC16	uint16	Wh	W
set_unlock_plug Triggers plug unlock; only valid when station is in suspended state.	5012	FC16	uint16		W
set_enable Enables or disables the charging station; 0 disables, 1 enables.	5014	FC16	uint16		W
set_phase_switch_source Selects the communication channel that controls phase switching via contact X2.	5050	FC16	uint16		W
set_trigger_phase_switch Triggers a 1-phase to 3-phase switch or vice versa via contact X2.	5052	FC16	uint16		W