Safety Requirements
The MX-3P wires to the control coil outputs of an existing three-phase starter. The panel contains live 415V AC three-phase mains — all work must be performed with the mains supply fully isolated, locked off, and proved dead.
- 1Isolate the main circuit breaker or switch-disconnector feeding the three-phase starter panel. Lock out and tag out before opening the enclosure.
- 2Prove dead at all three phase terminals (R, S, T) using a calibrated voltage tester before touching any internal wiring.
- 3415V AC three-phase panels must be worked on by a qualified electrician. The MX-3P control wiring (12V DC, RS485) can be handled by a competent technician once the mains is isolated.
- 4Never connect MX-3P V+ or RS485 terminals to any mains voltage — these terminals are 12V DC only.
- 5All existing mains wiring (phases R/S/T, motor terminals U/V/W, overload relay) remains untouched — only the contactor coil control wiring is modified.
Tools Required
Flat-Head Screwdriver (3 mm)
For MX-3P control terminal screws (RS485, 12V DC, coil outputs)
Flat-Head Screwdriver (5 mm)
For contactor coil terminal screws
Wire Strippers
For preparing 1.0 mm² and 1.5 mm² control cable ends
Multimeter / Voltage Tester
To prove dead at mains terminals before work; to verify 12V DC after power-up
RS485 Shielded Twisted-Pair
1.0 mm² shielded cable for RS485 A/B from module to gateway
1.5 mm² Control Cable
For wiring from MX-3P coil output terminals to contactor coil A1 terminals
Clamp Meter
To measure motor running current during commissioning
What's in the Box
MX-3P Control Module
Main IoT control module for DIN rail mounting
RS485 Terminal Block
2-position screw terminal for RS485 A and B wiring
12V DC Input Terminal
2-position screw terminal for control power
Coil Output Terminal Block
3-position screw terminal for DOL coil or main/star/delta coil outputs
Phase Sense Input Terminal
3-position terminal for R, S, T phase sensing wires
DIN Rail Clip
Spring clip for 35 mm DIN rail mounting
Quick Installation Card
Printed terminal wiring diagram and commissioning checklist
Removing an Old Smart Controller
The MX-3P is a retrofit controller for existing three-phase starter panels. Keep the main power section, contactors, overload relay, and motor cabling intact, and remove only the legacy smart or auxiliary control logic before installing the MX-3P.
- 1Do not disturb the existing R, S, T mains power wiring, motor U, V, W wiring, or overload relay current path unless the starter is being repaired separately.
- 2Remove or isolate old timer relays, pressure switches, float controls, or manual selector switch outputs only from the contactor coil control path that the MX-3P will take over.
- 3If the panel already includes another PLC, relay logic card, or smart controller, ensure its output to the contactor coil is fully disconnected to avoid dual-command conflicts.
- 4Retain hardware overload and interlock circuits that are already functioning correctly, especially in star-delta panels.
- 5If the existing starter panel has damaged contactors, welded contacts, or unreliable overload protection, repair or replace those components before installing the MX-3P.
Guided Help Center
Identify old PLC, timer, relay card, or smart controller outputs currently connected to the starter control circuit.
Panel Mounting
Clip the MX-3P onto the existing DIN rail inside the panel. The module requires approximately 50 mm of free DIN rail space.
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- 1With mains isolated and proved dead, open the panel enclosure.
- 2Identify a free DIN rail section beside the existing contactor(s). If space is tight, add a DIN rail extension bracket.
- 3Clip the MX-3P module onto the DIN rail — press until the spring clip engages.
- 4Keep 12V DC and RS485 wiring in the cable duct away from 415V mains conductors — at least 50 mm physical separation or a metal duct divider.
- 5Fit the 12V DC DIN rail power supply adjacent to the MX-3P — this supply must have a minimum 1A rating.
Guided Help Center
Open the panel after isolation and identify free DIN rail space near the existing starter.
Control Coil Wiring
For DOL starters, the MX-3P has one coil output (OUT-1) that controls the main contactor coil A1. For star-delta starters, the MX-3P-SD variant has three outputs: MAIN, STAR, and DELTA for the three contactors.
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- 1Locate the coil terminal A1 on the main contactor (DOL) or on the main, star, and delta contactors (star-delta).
- 2Disconnect the existing control wire from A1. Keep the A2 side connected — it goes to Neutral.
- 3DOL: Connect MX-3P OUT-1 to main contactor A1.
- 4Star-Delta: Connect MX-3P MAIN to main contactor A1; STAR to star contactor A1; DELTA to delta contactor A1.
- 5Connect phase sense wires: thin 1.0 mm² wire from each phase R, S, T (tapped from the mains bus bars or input terminals after the isolator) to MX-3P phase sense terminals R, S, T. These are voltage-sensing only — no load current flows through them.
- 6Connect 12V DC V+ and V− terminals from the DIN rail power supply to MX-3P.
- 7Connect RS485 cable: A core → RS485-A, B core → RS485-B. Shield to earth at panel end only.
Guided Help Center
Identify whether the existing starter is DOL or star-delta before connecting the MX-3P outputs.
Commissioning & First Start
- 1Restore 12V DC power to the MX-3P first — confirm the LED illuminates (green or flashing blue).
- 2Restore three-phase mains supply to the panel.
- 3Complete Gateway Linking — see the Gateway Linking guide — before issuing any motor start commands.
- 4From the app, tap Manual Control → Start. The main contactor should energise with an audible click.
- 5Measure motor current on all three phases using a clamp meter — confirm balanced current within 5% across R, S, T.
- 6If motor runs in the wrong direction: isolate, then swap any two motor phase connections (U-V or V-W) at the motor terminal box. Do NOT swap phases at the mains input — this affects all other loads on the supply.
- 7Confirm phase-loss detection: remove one phase sense wire temporarily and verify the app reports a phase loss alarm within 5 seconds. Restore and reset.