In smaller sized greenhouses, 
a manual program opened and closed by hand could possibly be installed. These work simplest when the Rack Drive For Greenhouse screen materials is backed by a track system.
Start time – when in the morning will the display system start operation
Stop time – when in the afternoon will the display screen 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 limits of temperature desired
Maximum/minimum humidity – What are the limitations of humidity desired
Gap positions – this units the percent open up or close placement under different circumstances such as in early stages a winter morning to reduce thermal shock or through the summer to supply better shading. The gap guidelines and speed of movement can be controlled in a few systems.
Time delay – under changeable climate this avoids frequent opening and closing
Wind speed – To reduce high temperature loss, the screen could be closed early below high wind speed conditions
Snow detection – this can open the screen and turn on the heat when it starts to snow.
The standard system uses nylon monofilament or stainless steel cables to aid the screen material. The screen material can possibly rest on top of the network of cables or end up being 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 either with a manual change or electronic controller.
Based on the over, the grower must 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.