Installers reach for the 540R2 when a 35 Nm motor leaves no margin on the tube and a 50 Nm motor costs more lift than the assembly needs. Somfy rates reference 1240556 at 40 Nm and 14 rpm, on a star head, inside the LT50 family. Radio control comes built into the head. You pair a handheld, set two limits, and leave the wall alone.
Torque sizing decides this motor
Forty newton metres converts to 354 in-lb. That figure carries a wide exterior solar screen or a rolling shutter curtain on a 2 in or 2.5 in tube without running the motor near its ceiling. Speed stays at 14 rpm, the standard exterior pace across the Altus RTS range, which keeps a tall shutter moving at a rate the drive and the curtain tolerate.
Size from the finished assembly, not the fabric alone. Add the weight of the tube, the hembar, the curtain and any bottom rail, then multiply by the radius the roll reaches at full wrap. Our motor sizing guide walks the arithmetic with worked numbers. Installers who land between two ratings take the higher one. A motor working inside its rating runs cooler and holds limits longer.
Screens and shutters the 540R2 drives
Somfy publishes six applications for this reference: awnings, exterior solar screens, rolling shutters, interior window coverings, projection screens and retractable insect screens. Exterior solar screens and retractable awnings take the bulk of the 40 Nm units in the field. Rolling shutters come next, where the torque matters on an aluminum curtain at full height. One spare on a dealer shelf covers several of those jobs.
The IP 44 rating backs the exterior work. Somfy rates the motor from -4 F to 158 F in service and from -4 F to 176 F in storage, so a south-facing screen box in Phoenix and an unheated garage in Minnesota both sit inside the published window.
Verified specs for reference 1240556
| Specification | Published figure |
|---|---|
| Torque and speed | 40 Nm (354 in-lb) at 14 rpm |
| Power supply | 120 V / 60 Hz, 108 V to 132 V |
| Rated current | 1.8 A |
| Operating consumption | 210 W |
| Standby consumption | 0.37 W |
| Radio | 433.420 MHz, 12 channels, rolling code with 16 million possibilities |
| Radio range | 656.2 ft open field |
| Head type | Star |
| Limit switches | Electronic, 250 turn capacity, repeatability under +/- 3 |
| Minimum tube inner diameter | 1.85 in |
| Motor diameter | 1.97 in |
| External diameter | 1.77 in |
| Unwrapped length | 26.1 in |
| Riveting position distance | 25.2 in |
| Cable | SJTW, 3-wire, 9.84 ft, white, stripped ends |
| Ingress protection | IP 44 |
| Insulation class | Class I |
| Thermal protection | 5 min |
| Operating temperature | -4 F to 158 F |
| Storage temperature | -4 F to 176 F |
| Warranty | 5 years |
Figures come from Somfy's published data for reference 1240556.
Tube, crown and drive, and bracket fit
The 1.85 in minimum internal tube diameter sets the floor. Measure inside the tube, not across the outside, and allow for the seam weld on a roll-formed section. A 2 in round tube clears the motor body with room for the crown. Anything tighter will bind the motor at the crown shoulder and strain the drive.
Pick the crown and drive to match the tube profile. The LT50 2.5 in round crown and drive set handles round tube in that size, and the octagonal LT50 70 mm crown and drive set covers 70 mm octagonal tube on shutter work. The crown locates the idle end of the motor inside the tube. The drive transfers torque to the tube wall. Fit the wrong profile and the tube spins on the drive under load.
Mounting hangs off the star head. The LT50 star head motor bracket takes the head directly and suits a clean new box. For a retrofit into an existing bracket pattern, the LT50 universal motor bracket gives more hole choices on the same star head. Check your drop-in depth before ordering. The motor needs 26.1 in of clear length plus the crown and bracket stack.
RTS control and pairing
Radio Technology Somfy lives in the motor head, so the only wire leaving the motor carries line power. Somfy publishes 12 channels and 656.2 ft of open-field range at 433.420 MHz, with a rolling code drawn from 16 million possibilities. Metal shutter boxes and stucco mesh cut that range, and installers plan a repeater or a closer control point on long runs.
A Situo 1 Channel RTS Pure remote covers a single motor and gets a new installation running in minutes. Telis handhelds and DecoFlex wall transmitters join the same motor across more channels. Somfy also lists the TaHoma switch for this reference, which brings the shutter into app control and voice routines alongside the rest of a Somfy house.
Wiring and limit setup notes
Somfy supplies the motor with a 9.84 ft white SJTW 3-wire lead, stripped, with no plug. Class I insulation means the ground conductor carries a real job here. Land it. An electrician is not required for the pairing or the limits, and many dealers terminate the lead into a junction box inside the screen box or the shutter headbox.
Limits are electronic with 250 turns of capacity, which covers a tall shutter curtain with margin. You set upper and lower positions from the remote once the motor answers. Repeatability runs under plus or minus 3, tight enough that a bank of shades lines up across a facade. Thermal protection cuts in after 5 min of continuous running and resets once the motor cools, so stage long commissioning cycles with a pause between them.
The Somfy 540R2 Altus RTS 120V 3-Wire Motor (1240556) ships as the motor and lead. Add the crown and drive for your tube profile and a bracket that matches your box. One RTS control pairs it. Somfy backs the motor for 5 years. Dealers stocking exterior work keep the 40 Nm unit alongside the 35 Nm and 50 Nm ratings, since most screen and shutter jobs land across those three figures.
Questions installers ask
What tube size does the Somfy 540R2 need?
Somfy publishes a 1.85 in minimum internal tube diameter for reference 1240556. A 2 in round tube or a 70 mm octagonal shutter tube both clear it. Measure the inside diameter at the seam, pick a crown and drive set matching the profile, and confirm the tube gives you 26.1 in of clear motor length plus the crown and bracket stack.
How much weight will 40 Nm lift?
Torque capacity depends on the roll radius, not the weight alone. A 40 Nm motor at 354 in-lb carries a wide exterior solar screen or an aluminum rolling shutter curtain on a 2 in tube. Total the assembly weight, multiply by the full-wrap radius in inches, and keep the result under 354 in-lb with margin.
Which remotes pair with the 540R2 Altus RTS?
Any Somfy RTS transmitter pairs with it. Situo handhelds, Telis handhelds, DecoFlex wall transmitters, Smoove wall transmitters and the TaHoma switch all speak the 433.420 MHz RTS protocol this motor listens on. Somfy gives the motor 12 channels, so one head answers several controls across a house or a facade.
Does the 540R2 come with a plug?
Somfy supplies a 9.84 ft white SJTW 3-wire lead with stripped ends and no moulded plug. Installers terminate it in a junction box or fit a plug to suit the local code. Class I insulation means the ground conductor gets landed. Confirm the lead against the motor you receive before you cut anything.
Shade Motors Direct is an authorized source for genuine Somfy motorized window shade, blind, and drapery parts.
