(MMS) Client/Server - ALSTOM Signaling Inc.

General Description1.6. CONTROL SYSTEMMMS supports the following control systems: VPI ® IIiVPIThe control system is generally comprised of: One Vital processor board that coordinates the Vital aspects of system operationUp to four non-vital processor boards. A non-vital processor board coordinatesnon-vital communications and handles non-vital I/O. Non-vital only controlsystems containing only non-vital processor boards are also feasible.1.6.1. VPI ® II/iVPI ApplicationVarious VPI ® II/iVPI boards contain user programming that is specifically developed forthe location where the system is installed. The programming for a particular board iscalled an application. Each application includes logic statements that control the board'sbehavior. Logic statements manipulate variables, which are memory locationscontaining some discrete piece of information such as the status of an I/O port or amessage bit. The most common logic statement is the Boolean equation, which logicallycombines the values of several variables to get a single True or False value and thenassigns that value to one or more results. Vital processor boards are capable ofprocessing only Boolean equations. Non-vital processor boards are also capable ofprocessing integer equations as well as more complex statements such as subroutinesand IF/ELSE.The application programming for a board is produced by compiling graphical or textbased input files using software tools contained in the Computer-Aided ApplicationProgramming Environment (CAAPE). The compile process of the CAAPE optionallyproduces a report file which includes, among other things, a symbol table mappingmemory locations to variable names and a logic section listing the logic statements inthe application. Report files for Vital processor applications have an "LVC" extension;report files for non-vital processor applications have an "LCS" extension.P2528, Rev. Aug/12 1–6 Alstom Signaling Inc.