In smaller sized greenhouses, a manual system opened and closed yourself could be installed. These work simplest when the screen materials is backed by a monitor system.
Start time – when in the morning will the display screen system start operation
Stop period – when in 
the afternoon will the display 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 limitations of temperature desired
Maximum/minimum humidity – What are the limits of humidity desired
Gap rack drive for greenhouse china positions – this sets the percent open or close position under different conditions such as early on a winter early morning to reduce thermal shock or through the summer to supply better shading. The gap guidelines and speed of motion can be controlled in some systems.
Time delay – under changeable climate this avoids frequent starting and closing
Wind speed – To lessen warmth loss, the screen could be closed early below high wind speed conditions
Snow detection – this may open the display and turn on heat when it begins to snow.
The standard system uses nylon monofilament or stainless 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 moves the leading edge of the screen material. Control is certainly either with a manual switch or electronic controller.
Based on the above, the grower is required to enter the next parameters into the controller:
A weather station is required to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.