To most common form of motorization found in roller shutters and roller blinds are tubular motors. The design and flexibility of tubular motors means ther are also used widely in retractable screens, roofing shutters, wind up awnings, and other roll up applications.
A tubular motor is design to fit within a tubular axle in the roll up application. Thus, they are tubular in appearance. Generally comprising a metal or plastic tube casing they have a flange or drive wheel at one end and a fixing means at the other end. In extremely simplistic terms the tubular motor comprises a low speed AC electric motor driving a series of planetary gear systems in series that are mounted in the tube of the motor. The reducing effect of these planetary gear systems gives the low speed and torque required to lift the load.
The oldest and most common type of limit stops for tubular motors are mechanically set limits. These limits are set by the installer by when in situ by pressing a series of buttons on the tubular motor, or perhaps by using a remote control. Basic electronic pulse counting and an optical encoder wheel allow the tubular motor to 'remember' the limit stops. Newer more sophisticated electronics allows for more advanced electronics only limit settings in newer tubular motors. This means the installer can set limit positions via remote control without actually needing the physically access the tubular motor. These newer tubular motors can also remember intermediate positions allowing the end user to not only have 'all up' or 'all down' positions but also 'half up' positions.
Typically a tubular motor is fitted within a tubular axle that is designed to rotate. One end of the tubular motor is fixed to the axle (via a screw or rivet) and thus the tubular motor cannot rotate independently of the axle. The drive wheel end of the tubular motor can now be fitted to a stub axle or some other fixed axle and is prevented from rotating. Now when the tubular motor is powered the drive flange of the tubular motor doesn't turn, but the tubular section of the motor which is fixed to the axle does. Thus the axle rotates.
Typically a tubular motor is powered by the household electricity system, usually requiring a licenced electrician to install one properly. However, some models are available that run from low voltage DC power.