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29 Jan 2020, Pintaudi Giorgio, Info, Force triggering of idle routine of a frontend        02 Feb 2020, Konstantin Olchanski, Info, Force triggering of idle routine of a frontend           02 Feb 2020, Pintaudi Giorgio, Info, Force triggering of idle routine of a frontend        03 Feb 2020, Stefan Ritt, Info, Force triggering of idle routine of a frontend           04 Feb 2020, Pintaudi Giorgio, Info, Force triggering of idle routine of a frontend              07 Feb 2020, Stefan Ritt, Info, Force triggering of idle routine of a frontend                 07 Feb 2020, Pintaudi Giorgio, Info, Force triggering of idle routine of a frontend                    09 Feb 2020, Stefan Ritt, Info, Force triggering of idle routine of a frontend                       10 Feb 2020, Konstantin Olchanski, Info, Force triggering of idle routine of a frontend                    12 Feb 2020, Stefan Ritt, Info, Force triggering of idle routine of a frontend

Message ID: 1805     Entry time: 02 Feb 2020     In reply to: 1802 Author: Pintaudi Giorgio  Topic: Info  Subject: Force triggering of idle routine of a frontend

Dear Konstantin, thank you very much for the explanation. I already have an idea of how to solve my problem by bypassing the class driver altogether or by slightly modifying the mfe.cxx frontend. But either way is not very elegant. If there was a way to do what I need easily and without writing much code, I would obviously choose that. So let us wait for Stefan opinion! Thanks again Giorgio Quote: > Hi, Giorgio - I think you encountered a fundamental problem with what to do at the begin of > run. There are two ways of thinking about it. > > Some experiments want to start the run as quickly as possible, so they do not want > begin_of_run() to do too much stuff. > > Other experiments want to record all the current settings and conditions before starting a > run, their begin_of_run() will read all the slow controls, interrogate all the power supplies, > read all the voltages, temperatures, pressures, etc. By necessity this will slow down the > starting of the run quite significantly. > > The best I understand the midas class driver structure, it is more geared for the first case - > fast starting of runs. > > The thinking behind this choice considers the nature of most slow control data in typical > physics experiments: > - if the data does not change quickly (say, room temperature, atmospheric pressure, etc), > and you read it say every 1 minute, then you do not need to read it again at begin run time - > the 1 minute old measurement is still good enough - nothing changed much since then > - if the opposite is true, the data changes wildly (i.e. detector high voltage current goes up > and down in response to the quickly changing beam current), measuring it at the start of > the run does us no good - by the time the first event comes around, it has already changed > completely. > > Hopefully Stefan can help you with your specific problem, he has better understanding of > the midas class drivers. > > > K.O.

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