Rotation of the dome is measured by a rotary encoder, and the home position is confirmed by the home sensor. The combination of these allows for very precise positioning of the dome.
The encoder is required, except for stepper motors; without it, the system cannot track dome position accurately. If the encoder does not detect motion when the dome is running, the system will stop and issue a warning.
The encoder can be coupled either to the motor axle—downstream of any reduction gearing—or directly to the dome rack, using a dedicated coupling. A non-friction coupling is preferable in either case, to avoid slippage.
On the shutter's opening, the encoder is optional—open and close positions come from the limit switches—but we recommend fitting one anyway: it lets the system catch a stalled or slipping motor as an extra safety check. Flaps never take an encoder.
NPN, 5V DC quadrature encoder required. The system will track up to 2 KHz step pulses, which is clearly overkill. Anything above a few counts per degree will provide ample resolution for dome tracking.