In smaller greenhouses, a manual system opened and closed yourself could be installed. These work easiest when the screen materials is backed by a track system.
Start time – when in the morning will the screen system start operation
Stop time – when in the afternoon will the screen system stop operation
Light level – in what light intensity will the screen be activated either to open or close
Maximum/minimum temperature – what are the limits of temperature desired
Maximum/minimum humidity – 
What are the limitations of humidity desired
Gap positions – this sets the percent open up or close placement under different conditions such as early on a winter early 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 starting and closing
Wind speed – To lessen heat loss, the screen could be closed early below high wind speed conditions
Snow detection – this may open the display screen and turn on the heat when it begins to snow.
The standard system uses nylon monofilament or stainless steel cables to support the screen materials. The screen rack drive for greenhouse china material can either rest along with the network of cables or become suspended by hooks from the cables. A gearmotor powers a drum or rack and pinion that movements the industry leading of the screen materials. Control is either with a manual switch or electronic controller.
Based on the above, the grower must enter the following parameters in to the controller:
A weather station is needed to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.