A source of constant signal Constant
I.V.Chernyh. "Simulink: the tool of modelling of dynamic systems" 1. The general data Program Simulink is the appendix to package MATLAB. At modelling with use Simulink the principle of visual programming according to which, the user on the screen from library of standard blocks creates model of the device is realised and carries out calculations. Thus, unlike classical ways of modelling, the user does not need to study thoroughly the programming language and numerical methods of mathematics, and enough the general knowledge required at work on the computer and, naturally, knowledge of that subject domain in which it works. Simulink is independent enough tool MATLAB and at work with it at all it is not required to know itself MATLAB and its other appendices. On the other hand access to functions MATLAB and its other tools remains opened and they can be used in Simulink. A part of a part packages the tools which are built in in Simulink (for example, LTI-Viewer have appendices Control System Toolbox - a package for management system engineering). There are also additional libraries of blocks for different scopes (for example, Power System Blockset - modelling of electrotechnical devices, Digital Signal Processing Blockset - a set of blocks for working out of digital devices, Neural Network Blockset - a set for work with neural networks and т.д). At work with Simulink the user has possibility to modernise library blocks, to create own, and also to make new libraries of blocks. At modelling the user can choose a method of the decision of the differential equations, and also a way of change of modelling time (with the fixed or variable step). During modelling there is a possibility to watch the processes occurring in system. The special devices of supervision which are a part of library Simulink are for this purpose used. Results of modelling can be presented in the form of schedules or tables. Advantage Simulink consists also that he allows to fill up libraries of blocks by means of subroutines written both in language MATLAB, and in languages With ++, Fortran and Ada. 7. Installation of parametres of calculation and its performance Before performance of calculations it is necessary to set calculation parametres preliminary. The task of parametres of calculation is carried out in the control panel of menu Simulation/Parameters. The window of adjustment of parametres of calculation has 4 вкладки: · Solver (Calculation) - Installation of parametres of calculation of model. · Workspace I/O (Data input/conclusion in working area) - Installation of parametres of data exchange with working area MATLAB. · Diagnostics (Diagnostics) - the Choice of parametres of a diagnostic mode. · Advanced (In addition) - Installation of additional parametres. · we Will dwell on Solver (Calculation) - Installation of parametres of calculation of model. These elements are divided into three groups (fig. 7.1): Simulation time (the Interval of modelling or, otherwise, calculation time), Solver options (calculation Parameters), Output options (conclusion Parameters).
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Installation of parametres of calculation of model
Simulation time (an interval of modelling or calculation time)
Calculation time is set by instructions initial (Start time) and final (Stop time) values of time of calculation. Initial time, as a rule, is set equal to zero. The size of final time is set by the user proceeding from conditions of a solved problem.
Solver options (calculation parametres)
At a choice of parametres of calculation it is necessary to specify a way of modelling (Type) and a method of calculation of a new condition of system. Two variants are accessible to parametre Type - c fixed (Fixed-step) or with variable (Variable-step) step. As a rule, Variable-step it is used for modelling of continuous systems, a Fixed-step - for discrete.
Calculation performance
Calculation start is carried out by means of a choice of point of menu Simulation/Start or tool na 
of the panel of tools or ^T. Calculation process can be finished ahead of schedule, having chosen point of menu Simulation/Stop or tool 
or ^С. Calculation also can be stopped (Simulation/Pause) and then to continue (Simulation/Continue).
The basic groups of blocks
1. Continuous - linear blocks.
2. Discrete - discrete blocks.
3. Functions and Tables - functions and tables.
4. Math - blocks of mathematical operations.
5. Nonlinear - nonlinear blocks.
6. Signals and Systems - signals and systems.
7. Sinks - registering devices.
8. Sources - sources of signals and influences.
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9. Subsystems - blocks of subsystems.
Let's consider some blocks entering into these groups
Sources - sources of signals
A source of constant signal Constant
Appointment: Sets a constant signal on level.
Parametres:
1. Constant value - a constant.
2. Interpret vector parametres as 1-D - to interpret a vector of parametres as one-dimensional (at the established tag). The given parametre meets at the majority of blocks of library Simulink. Further it will not be considered.
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