In smaller greenhouses, a manual system opened and closed by hand could be installed. These work Motor Gearboxes For Greenhouse easiest when the screen materials 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 intensity will the screen be activated either to open or close
Maximum/minimum temperature – what exactly are the limitations of temperature desired
Maximum/minimum humidity – What are the limits of humidity desired
Gap positions – this models the percent open up or close position under different circumstances such as early on a winter morning to reduce thermal shock or during the summer to provide better shading. The gap measures and speed of movement can be controlled in some systems.
Time delay – under changeable weather conditions this avoids frequent opening and closing
Wind speed – To lessen heat loss, the screen could be closed early below high wind speed conditions
Snow detection – this can open the screen and turn on heat when it begins to snow.
The typical system uses nylon monofilament or stainless cables to aid the screen materials. The screen material can possibly 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 moves the leading edge of the screen material. Control can be either with a manual change or electronic controller.
Based on 
the over, the grower is required to enter the following parameters into the controller:
A climate station is needed to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.