In smaller sized greenhouses, a manual system opened and closed by hand could possibly be installed. These work easiest when the screen material is supported by a monitor system.
Start time - when each morning will the display screen system start operation
Stop time - when in the afternoon will the display system stop operation
Light level - at what light strength will the screen end up being activated either to open up or close
Maximum/minimum temperature - what exactly are the limitations of temperature desired
Maximum/minimum humidity - What exactly are the limitations of humidity desired
Gap positions - this pieces the percent open or close placement under different circumstances such as early on a winter early morning to lessen thermal shock or through the summer to Motor Gearboxes For Greenhouse provide better shading. The gap guidelines and speed of movement can be controlled in some systems.
Time delay - below changeable climate this avoids frequent opening and closing
Wind speed - To lessen high temperature loss, the screen can be closed early under high wind speed conditions
Snow detection - this may open the display screen and turn on heat when it begins to snow.
The standard system uses nylon monofilament or stainless steel cables to aid the screen material. The screen material can either rest on top of the network of cables or become suspended by hooks from the cables. A gearmotor powers a drum or rack and pinion that movements the leading edge of the screen materials. 
Control is certainly either with a manual change or electronic controller.
Based on the over, the grower is required to enter the next parameters in to the controller:
A climate station is required to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.