I read in the PROFIBUS PA specs that the max length of EACH spur is 30/60/120 m, but in PROFIBUS DP we have defined the spur length parameter as TOTAL spur length. Can you explain?

Because the baudrate is relatively low with PROFIBUS PA, spur lines are allowed to be long without disturbing the data communication and we can assign a fixed maximum length per spur / per device. With PROFIBUS DP it is a different story; the high baudrate limits the spur line length. If we would fix the maximum length per device, it would only be 20 cm per spur for 32 devices and that would not make sense.

To solve this we define it as a total sum of all spurs together so that the end-user has more flexibility, because not all devices require a spur line. More.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.