ROAMiQ Dual Channel Relay: Happijac bed lift wiring guide
Wire the ROAMiQ Dual Channel Relay (RQ-MCM) into a Happijac bed lift control box. The relays stand in for the UP and DOWN switch contacts, the wall switch moves to the ground-triggered inputs, and the bed runs from the switch or the ROAMiQ app.
What this setup does
A Happijac bed lift already has its own control box. That box runs the motor, manages its brake mechanism, watches its own limits, and waits for a signal from the wall switch telling it to go up or down. ROAMiQ doesn't replace any of that. The Dual Channel Relay (SKU RQ-MCM) becomes the switch.
- Relay 1 and Relay 2 each give you a clean, isolated contact (NO, C, NC). One closes the control box's UP circuit and the other closes its DOWN circuit, just like pressing the wall switch.
- Your existing wall switch moves to the relay's switch inputs. Press it and ROAMiQ closes the matching relay, so the switch works exactly as before. You also get control from the ROAMiQ app and your automations.
Why a relay, and not our Motor Relay V2
The Motor Relay V2 is built to power a motor directly. Its output is solid-state: it meters current like a valve instead of opening and closing a contact. A Happijac control box is expecting a plain mechanical switch on its UP and DOWN wires, and we can't predict how its input circuit reacts to a solid-state output. The Dual Channel Relay gives the box a real contact that opens and closes like the switch it was designed around. For a Happijac control box, use the Dual Channel Relay.
The terminals
Every screw terminal has its name printed on the board next to it. Match the wire to the printed name.
Power and switch inputs (6-position block)
| Printed name | What it is |
|---|---|
| 12V IN | +12V feed that powers the relay board |
| GND | Ground |
| IN3 | Spare switch input (not used here) |
| IN2 | Switch input for UP (Close in the app) |
| IN1 | Switch input for DOWN (Open in the app) |
| GND | Ground, for your wall switch's common |
Relay contacts (two 3-position blocks)
| Printed name | What it is |
|---|---|
| NO1 / C1 / NC1 | Relay 1: normally open, common, normally closed |
| NO2 / C2 / NC2 | Relay 2: normally open, common, normally closed |
The relay contacts are fully separate from the board's power. Nothing on NO, C or NC connects to 12V IN or GND, so you can switch whatever the Happijac control box's switch circuit uses.
Wiring map
| From | To | Job |
|---|---|---|
| Fused +12V | 12V IN | Powers the relay board |
| Chassis ground or battery negative | GND | Board ground |
| Happijac switch common wire | C1 and C2 (jumper the two together) | Shared side of both "switch" contacts |
| Happijac UP wire | NO1 | Relay 1 closes UP |
| Happijac DOWN wire | NO2 | Relay 2 closes DOWN |
| Wall switch common (center) terminal | GND (the one next to IN1) | Switch return |
| Wall switch UP terminal | IN2 | Tells ROAMiQ "UP is pressed" and closes Relay 1 |
| Wall switch DOWN terminal | IN1 | Tells ROAMiQ "DOWN is pressed" and closes Relay 2 |
| Nothing | NC1, NC2, IN3 | Leave empty |
Step by step
Kill power
Pull the fuse for the Happijac bed lift and make sure the relay board has no 12V on it.
Free up the wall switch
Take the wall switch out of the wall and label each Happijac wire as you remove it: common, UP and DOWN. Then disconnect all Happijac wires from the switch. The wall switch should be connected to nothing but the ROAMiQ relay once you're done.
Wire the Happijac side to the relays
Connect the Happijac common wire to C1, and add a short jumper from C1 to C2. Connect the UP wire to NO1 and the DOWN wire to NO2. Leave NC1 and NC2 empty.
Wire the wall switch to the inputs
Connect the switch's common (center) terminal to GND, its UP terminal to IN2, and its DOWN terminal to IN1.
Wire power
Connect a fused +12V source to 12V IN and ground to GND.
Test
Restore power. Press and hold the wall switch UP for a moment, then DOWN, and watch the bed. Then try Open and Close from the ROAMiQ app.
How it behaves
- From the wall switch: it's hold-to-run. The relay stays closed only while you hold the switch, so the bed stops when you let go.
- From the app: Open or Close starts the bed moving and it keeps going until you press Stop, the Happijac box reaches its own travel limit, or the relay's runtime limit ends the run (30 seconds by default, adjustable from 5 to 120 seconds). Stay with the bed while it moves.
- Only one direction at a time. ROAMiQ never closes both relays at once, and it pauses briefly before switching direction.
- Fail-safe: a loose or broken switch wire does nothing, and both relays open on power-up and when power is lost, so the bed won't move on its own. If the relay board loses power, the wall switch stops working too, because it now runs through ROAMiQ.
Troubleshooting
Nothing happens when I press the wall switch.
- Check power. Confirm 12V on 12V IN and a solid ground on GND, and check both the Happijac fuse and the relay's fuse.
- Check the switch wiring. The switch common must go to GND, not to a Happijac wire. Each outer terminal goes to IN1 or IN2.
- Check the relay side. The Happijac wires must be on NO and C, and the jumper between C1 and C2 must be in place.
The bed goes the wrong way from both the wall switch and the app.
The Happijac UP and DOWN wires are swapped. Kill power and swap the wires on NO1 and NO2.
The app works but the wall switch is backwards.
The switch's UP and DOWN terminals are swapped. Kill power and swap the wires on IN1 and IN2.
The bed moves on its own when the relay powers up.
A Happijac wire is on an NC terminal. Kill power immediately and move it to the matching NO terminal.
The bed stops partway when I use the app.
It's probably hitting the relay's runtime limit. If your bed needs longer than 30 seconds for a full run, raise the runtime limit in the ROAMiQ app.
Still stuck?
We are your installer on call. Reach ROAMiQ support and we will walk you through it.