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Modeling vacuum plumbing in Aeon's HACS

Overview

A vacuum plumbing system can be viewed simply as a network of valves connecting enclosed chambers. The HACS model starts with these two elements, and provides a several composite classes that define connections and implement common operations to greatly simplify process code.

Each element in the system is defined in the settings.xml file by listing its properties. First, define the most elementary devices, then proceed to the more complex. For the vacuum plumbing, a good order of construction is Chambers, Ports, Valves, Sections, VacuumSystems, GasSupplies.

Aeon often names Chambers and Ports by short, two- or three-letter mnemonics or abbreviations of their functions, and then names Valves from the Chambers or Ports they connect. For example, an inlet manifold might be named IM, and a variable temperature trap, VTT. A valve between them would be named v_IM_VTT. This is merely a convention. Device names may be any valid string.

Elements

Here are brief descriptions of the major HACS plumbing system classes, along with guidance for setting certain properties for particular purposes.

Whether, where, and when certain valves should appear in ValveLists
General guidelines (there may be exceptions)

ValveList.Close() and .Open() do not directly operate VacuumSystem v_HighVacuum or v_LowVacuum Valves. When either of those valves is present in a ValveList, the method invokes VacuumSystem.Isolate() or .Evacuate() instead.

Exclude (physically present) port valves (at the IP, VP, GRs, etc.) to have them ignored by general-purpose ValveList methods. This enables and requires their inclusion or exclusion to be determined by the process code, which is normally the desired functionality.

Gas supply valves usually may be included or omitted without affecting general-purpose functionality. It normally doesn't hurt to include them, but their absence normally does not matter, either, because they are essentially always closed (except briefly to admit gas). If a gas supply valve is included in a Section's Isolation list, and that list is ever Open()ed, the gas supply valve will be opened along with everything else. This most probably would be undesired; however, Isolation lists are never Open()ed in the general-purpose code.

 
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