BPM data combiner: requirements specification

Anstelle eines Lastenhefts

Motivation

The beam position monitors of BESSY~II are read out by electronic units. The existing ones are to be replaced by new units.

Below in the text he new units will be called “instrumentation devices” (or libera spark?) units.

The data these instrumentation device units provide are to be combined in such a fashion to

  • make it possible to swap out the old units to the new units sector per sector

    In the following text the new units are called

  • be able to operate the standard slow orbit feedback of the BESSY II machine

  • provide a consistent data set of the beam position monitors

    It shall represent the beam positiion monitor data in a consistent fashion to the user as soon as all bpm readers are “instrumentation devices units”.

Background

Standard operation of the units

Each beam position monitor (BPM) is handled by a dedicated unit. This unit provides the following data

  • x position in nm (or close to that)

  • y position in nm (or close to that)

  • counts since a synchronisation event: this ensures that all units provide a consistent count

This data are provided with an update rate of 0.1 Hz.

Failure modes to consider

  • Units can be unresponsive: i.e. they can fail to deliver data

  • Units can deliver erronous data: the machine operator must be able to mark them as erronous (done on the unit or here ? ).

Target:

  • Combine beam position monitor data of all beam position monitors in a consistent fashion: i.e. the readings of all beam position monitors of the new system are provided in a structure.

  • Provide the beam position in a manner so that the electronic units can be swapped out sector per sector.

Misc: naming

  • BPM data combiner: it combines the data to a single set

  • BPM data collector: it collects the data of the different units