Motorised curtains are the guest room function that most often generates a service call in the first year. Not because the motors are unreliable, but because the connection between motor and control system is made in a hurry at the end of a fit-out, usually after the curtain track is already installed and access is poor.
The wiring itself is straightforward. This article covers what connects where, how the control logic behaves, and the two commissioning steps that prevent most later complaints.
Two Connections, Two Purposes
A motorised curtain in a hotel room needs two separate things:
| Connection | Purpose | |
|---|---|---|
| Power | 220 V supply cable | Drives the motor |
| Control | RS485 signal via RJ45 | Carries open, close and stop commands from the RCU |
Keep these physically separate in the ceiling void. The most common cause of erratic curtain behaviour is a signal cable cable-tied along the length of the mains supply, picking up interference from the motor’s own switching.
The Power Side
The curtain motor has a 220 V supply lead. This is a normal mains connection and follows normal practice — supply from the room’s circuit, correctly protected, terminated in an accessible position.
One point to settle at design stage: should the curtain circuit be switched by the key card power switch, or remain live?
If it is switched, the curtain cannot be operated when the card is out — which means housekeeping cannot open curtains in a vacant room, and the room cannot be pre-set before arrival. Most properties keep the curtain circuit live and control it through the RCU instead.
The Control Side: RJ45 and RS485
The motor has an RJ45 socket for the control connection. Crimp a plug onto the control cable following the pin arrangement in the motor documentation, plug it into the motor, and land the other end on the RS485 signal terminals of the RCU host.
Two practical notes:
- Crimp carefully and test before the track is closed up. A marginal crimp works on the bench and fails once the connector is flexed into position above the pelmet. Once the curtain box is finished, getting back to that plug is genuinely difficult.
- Confirm the pin arrangement against the specific motor. RJ45 is a connector format, not a standard for what each pin carries. Different motors use different arrangements.
How the Control Logic Behaves
Curtain control from a wall panel is not simply on and off. The normal behaviour is press-stop-press:
- Press open — the motor starts opening
- Press open again — the motor stops at the current position
- Press open again — the motor resumes opening
- The motor continues until it reaches the open limit
Close works the same way. This lets a guest set the curtain to any intermediate position with one button, which matters in rooms where the guest wants daylight without exposure.
Where a room has both sheer and blackout curtains, each gets its own pair of buttons and its own motor. Attempting to control both from one button pair produces a control scheme that guests cannot predict.
The Two Commissioning Steps That Prevent Service Calls
1. Set the limits properly
The open and close limits define where the motor stops. Set them so the curtain closes fully with no light gap at the leading edge, and opens fully without the leading edge striking the end stop.
A limit set slightly short at the closed position produces a light gap that a guest notices at dawn — this is the single most common curtain complaint in hotels and it is a commissioning issue, not a product issue.
2. Test the full travel three times in each direction
Run the curtain fully open and fully closed, three cycles, and watch the leading edge. Fabric that catches, a track that binds, or a limit that drifts will show up here and is easy to correct while access is still open.
Both steps take a few minutes per room and remove most first-year curtain call-outs.
Coordination With Other Trades
Curtain motors are installed late, when the curtain contractor arrives, and the control cable is usually pulled much earlier by the electrical contractor. Three things to agree in advance:
- Cable termination point — where the control cable is left, and with how much slack. Leave enough to reach the motor in its final position plus a working loop.
- Access after the pelmet is closed — confirm whether the RJ45 connector will still be reachable. If not, testing before closing is mandatory rather than advisable.
- Who sets the limits — curtain contractor or controls contractor. This falls between scopes on many projects and ends up done by neither.
Recommended Uses
| Application | Configuration |
|---|---|
| Standard guest room | One motor for blackout, wall panel open/close, RS485 to RCU |
| Room with sheer and blackout | Two motors, two button pairs, independent control |
| Suite with multiple windows | Motor per window plus a group scene button |
| Renovation | Confirm existing track can accept a motor before specifying |
FAQ
Can the curtain be included in a scene?
Yes. Common scenes include a welcome scene on card insertion that opens the sheer curtain, and a sleep scene that closes the blackout. Scene logic sits in the RCU host.
Can the curtain be operated by voice?
Yes, where a voice device is integrated with the RCU. The command reaches the host and the host operates the motor, so the wall panel and voice control stay consistent.
What happens after a power failure?
The curtain stays where it was. On power restoration the motor should not move until commanded. Confirm this behaviour during commissioning rather than assuming it.
Can GLMZK supply curtain motors matched to the RCU?
Yes, and we can supply the control cable pre-terminated to reduce on-site crimping. Send the track length, curtain weight and window count with your enquiry.
Related Solutions
- Smart hotel RCU system
- Guest room control solution
- Hotel lighting and dimming control
- Smart hotel door plate
Contact GLMZK
GLMZK manufactures hotel RCU systems, curtain control modules, guest room control panels, door plates and key card power switches. We supply contractors and system integrators worldwide, with OEM design and full wiring documentation.
Send us your room type, key count and control point list, and we will return a panel schedule and wiring diagram.
Request a specification sheet and quotation | sales@smartguestroom.com