Troubleshooting

How to Fix

1. 1Confirm MX-1P is online in the app (green status) before issuing a start command.
2. 2Check that the MX-1P LED flashes or changes colour when a start command is issued — if it does not, the command is not reaching the module (check gateway RS485 connection).
3. 3Verify coil voltage selector on the MX-1P matches the contactor coil voltage (230V AC or 24V DC). A mismatch will prevent the contactor from energising.
4. 4Measure voltage across the contactor coil A1–A2 when a start command is active — should show coil-rated voltage. If 0V, check the wire from MX-1P output to A1.
5. 5If the overload relay NC contact is wired in series with the coil circuit, check that the overload relay has not tripped — press the overload relay reset button.
6. 6Check that mains supply is present at the contactor input (L1, N) — no mains means the motor cannot run even if the contactor energises.

How to Fix

1. 1A single-phase motor that hums but does not spin is almost always a capacitor fault — the motor has power but cannot generate starting torque.
2. 2Discharge the capacitor (short terminals through a 10 kΩ resistor), then test with a multimeter in capacitance mode — if the reading is more than 10% below the rated µF value, replace the capacitor.
3. 3Check capacitor wiring — confirm the capacitor is connected between the correct motor auxiliary winding terminals per the motor wiring diagram.
4. 4For PSC (submersible) motors: check the capacitor in the pump control box — it is the most common failure part on these motors.
5. 5Replace capacitor with same µF value and same or higher voltage rating (440V AC for run capacitors).

How to Fix

1. 1Check the overload relay current dial — it must be set to the motor nameplate FLA, not the starter rating or the supply breaker rating.
2. 2Measure motor running current with a clamp meter on the Line conductor — if it consistently exceeds nameplate FLA, there is a mechanical load issue (pump blocked, impeller worn, delivery valve closed).
3. 3If the overload trips immediately on every start: the current dial may be set below the motor's starting current — for Class 10 relays, the trip time at 6× FLA should be 4–10 seconds, which is enough for normal DOL starting.
4. 4Check the capacitor value — an oversized run capacitor causes higher running current and may trip the overload relay.
5. 5If recently replaced capacitor: verify the µF value matches the motor specification — oversize causes overcurrent.

How to Fix

1. 1Confirm 12V DC is present at the MX-1P V+ and V− terminals — the LED should be illuminated (green or blue). No LED means no power.
2. 2Check RS485 A and B polarity — swap the A and B wires at one end if the module is not detected after confirming power.
3. 3Verify the Modbus address set on the MX-1P matches the address the gateway is scanning — factory default is Address 1.
4. 4If multiple RS485 devices share the bus, confirm each has a unique Modbus address — duplicate addresses cause scan failures.
5. 5Check for a short between RS485-A and RS485-B with a multimeter (should not read 0 Ω) — a short will prevent all RS485 communication on the bus.
6. 6Fit a 120 Ω termination resistor between RS485-A and RS485-B at the furthest device if the bus run exceeds 10 metres.

How to Fix

1. 1Check the gateway connectivity indicator in the app — if the gateway itself shows offline, all devices on it will show offline. Restore gateway internet connection first.
2. 2If the gateway is online but only the MX-1P shows offline: check RS485 cable continuity between the module and the gateway.
3. 3Confirm 12V DC is present at the MX-1P (check LED). A power adapter failure or tripped 12V supply fuse causes the module to go offline.
4. 4Restart the 12V DC power supply to the MX-1P by switching it off and back on — the module should reconnect automatically within 60 seconds.
5. 5If the module intermittently goes offline: check for loose RS485 terminal connections at both ends. Tug each wire lightly — a loose screw terminal is a common cause of intermittent RS485 faults.