The first reason is to improve usage of LED monitors or tablets. Their prices became encouraging for wide usage. With these displays, one can indicate multiple layers of information in smart ways; furthermore, one can use them as touch panels for operation.

The second reason is that it is more convenient to mount displays externally. Doing so allows operators to easily adjust the position and angle of these displays to fit ones height or the way of operation. Also, externally mounted displays can be replaced as display technology advances year after year.

They are “robustness” and “flexibility”.
The word “robustness” refers not only to strength, but also the high rigidity needed to hold the display.
If the display is hard to read due to vibration of machinery, or if the display moves whenever you touch it, the quality or reliability of the whole machine equipment will be questioned.
Therefore, displays should be fixed by dedicated mounting systems in order to stable structural parts such as aluminum profiles.
Of course, the mounting system itself needs to have enough strength and rigidity.

On the other hand, “flexibility” to support convenient use for operators is another important requirement.
For example, it is convenient if the operator can move the position or angle of the display at the time of their rotation, or depending on the angle of sun-light from outside which changes over time.
Ideally, these adjustments of display position or angle should be made without tools.
Also, the joint should not get loosened after repeated movement of the display, and lastly the holding torque should be maintained.