In smaller sized greenhouses, a manual program opened and closed yourself could be installed. These work easiest when the screen material 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 – at what light strength will the screen end up being activated either to open or close
Maximum/minimum temperature – what exactly are the limitations of temperature desired
Maximum/minimum humidity – What exactly are the limits of humidity desired
Gap positions – this units the percent open or close position under different circumstances such as in early stages a winter early morning to reduce thermal shock or during the rack drive for greenhouse china 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 reduce high temperature loss, the screen could be closed early under 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 cables to support the screen materials. The screen material can either rest on top of the network of cables or be suspended by hooks from the cables. A gearmotor powers a drum or rack and pinion that techniques the leading edge of the screen materials. Control is usually either with a manual change or electronic controller.
Based on the above, the grower is required to enter the next parameters in to the controller:
A weather station is required to provide outdoor light level, temperature, humidity, wind and rain or snow conditions.