The Shelly Pro 4PM is a board-mounted device for serious loads, and a good deal of its configuration is not in the app. It is in its web interface: type its IP into a browser — something like http://192.168.1.70 — and from there you decide how its four relays and four inputs behave.
These are the settings that genuinely change how the installation works.
1. Input Mode — what kind of press it detects
This tells the Pro 4PM how to read whatever is wired to its input terminals: SW1, SW2, SW3 and SW4.
- Switch: for conventional wall switches, the kind with two stable positions. The Shelly reads the fixed position. This is what you want for lights or fans that should stay in one state.
- Button: for momentary switches that spring back, like a doorbell push. The Shelly registers an event on each press. This is the basis for firing automations without wiring any power.
2. Output Type — how each output reacts
This is where the real control sits, and it is set separately on each of the four relays.
- Toggle: the standard. On stays on; off stays off. General lighting, sockets, appliances.
- Momentary: the output gives a pulse. The relay closes for an instant — you set how long under Timers, with Auto OFF — and releases on its own. Essential for garage-door controller inputs, electric locks or irrigation: anything that needs a tap rather than a state.
- Edge: the relay flips state whenever the physical input changes. Uncommon, for very specific cases.
- Detached: decouples the physical inputs from the relays. The switches still report to the app and to Home Assistant, but no longer drive the device’s own relays. This is what you want when the switch should fire a scene instead of its own load.
- Activation: built for motion sensors. The input triggers and the relay switches on; if there is an Auto OFF timer, it restarts while the input stays active. Lights that hold while someone is there, extractors that keep running while the sensor sees something.
3. Action on Power On — what it does after a cut
Defines the state each relay lands in when power comes back.
- Turn ON: it switches on.
- Turn OFF: it switches off.
- Restore last known state: back to where it was before the cut. The sensible choice for almost everything, and the one that avoids surprises when the power returns.
- Current state of the switch: the relay follows whatever the physical switch says at that moment.
4. Output Protections — the limits that cut by themselves
This section exists to protect what is connected, and on a board device handling real loads it is not decoration.
- Overpower, in watts: the maximum per channel. Exceed it and the Shelly cuts. Useful with motors and heaters.
- Overcurrent, in amps: the maximum current before it disconnects.
- Overvoltage, in volts: if the incoming voltage rises past the limit it disconnects, protecting the load from a spike.
- Undervoltage, in volts: if it falls below, it disconnects too. This matters with motors and anything sensitive to a sag.
- Enable auto recovery: if a relay tripped on over- or undervoltage, it tries to switch back on once the condition clears, provided it was on beforehand.
5. Consumption Type — for third-party systems only
Lets you declare what kind of load is connected: light, motor, heater. It has no effect on the Shelly app. Its purpose is to let an external system such as Home Assistant classify and display the consumption properly. Check what values your system expects before filling it in.
6. Reverse Power Measurement — when it reads backwards
In particular installations the direction of the measurement can come out inverted: drawing when it should be exporting. If the readings make no sense for the circuit, turn this on. If they are coherent, leave it alone.
7. Lock Inputs — freezing the physical controls
With this on, the Shelly ignores any press on SW1 to SW4, whatever mode they are in. Useful for cleaning a switch without switching anything, for keeping small children from operating a circuit, for working on a fitting in peace, or for a holiday mode.
While it is on, the device answers only through the app, the web interface or Home Assistant. And if the input is also set to Detached, the physical switch does nothing whatsoever.
8. Reset Counters — back to zero
Clears the accumulated consumption data for the channels. Worth doing at the start of a new measurement period, or after swapping one significant load for another, so the history does not blend two different things.
In short
The app switches things on and off. The web interface is where the Pro 4PM stops being a relay with wifi and becomes a board device: measured pulses for a gate motor, protections per channel, and a defined behaviour for when the power comes back.