In smaller sized greenhouses, a manual system opened and closed yourself could be installed. These work easiest when the screen material is supported by a track system.
Start time – when each morning will the screen system start operation
Stop time – 
when in the afternoon will the screen system stop operation
Light level – in what light strength will the screen become activated either to open up or close
Maximum/minimum temperature – what are the Rack Drive For Greenhouse limitations of temperature desired
Maximum/minimum humidity – What exactly are the limits of humidity desired
Gap positions – this units the percent open up or close position under different conditions such as in early stages a winter morning to reduce thermal shock or through the summer to provide better shading. The gap measures and speed of movement can be controlled in some systems.
Time delay – below changeable weather conditions this avoids frequent starting and closing
Wind speed – To lessen high temperature loss, the screen could be closed early under high wind speed conditions
Snow detection – this may open the screen and turn on the heat when it begins to snow.
The standard system uses nylon monofilament or stainless cables to aid the screen material. 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 techniques the leading edge of the screen material. Control can be either with a manual switch or electronic controller.
Based on the above, the grower must enter the following parameters into the controller:
A weather station is required to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.