User manual MATLAB SIMEVENTS 3

[. . . ] SimEvents® 3 User's Guide How to Contact The MathWorks Web Newsgroup www. mathworks. com/contact_TS. html Technical Support www. mathworks. com comp. soft-sys. matlab suggest@mathworks. com bugs@mathworks. com doc@mathworks. com service@mathworks. com info@mathworks. com Product enhancement suggestions Bug reports Documentation error reports Order status, license renewals, passcodes Sales, pricing, and general information 508-647-7000 (Phone) 508-647-7001 (Fax) The MathWorks, Inc. 3 Apple Hill Drive Natick, MA 01760-2098 For contact information about worldwide offices, see the MathWorks Web site. SimEvents® User's Guide © COPYRIGHT 2005­2010 by The MathWorks, Inc. The software described in this document is furnished under a license agreement. The software may be used or copied only under the terms of the license agreement. [. . . ] These blocks are from the Simulink Ports & Subsystems library, and are not the same as the Discrete Event Inport and Discrete Event Outport blocks in the SimEvents Ports and Subsystems library. The subsystem also contains a block labeled "function. " 5 To change the number of inputs or outputs to the subsystem, change the number of Inport and Outport blocks in the subsystem window. You can copy, paste, and delete these blocks. 10-35 10 Controlling Timing with Subsystems Note Do not change the Initial output parameter in the Outport. If you need to define an initial output value for the signal, connect the Initial Value block to the output signal at the upper level of the model, outside the subsystem. 6 Drag other blocks into the subsystem window as appropriate to build the subsystem. This step is similar to the process of building the top level of hierarchy in your model, except that only certain types of blocks are suitable for use inside the subsystem. See "Blocks Inside Discrete Event Subsystems" on page 10-10 for details. 10-36 11 Plotting Data · "Choosing and Configuring Plotting Blocks" on page 11-2 · "Working with Scope Plots" on page 11-8 · "Using Plots for Troubleshooting" on page 11-10 · "Example: Plotting Entity Departures to Verify Timing" on page 11-11 · "Example: Plotting Event Counts to Check for Simultaneity" on page 11-15 · "Comparison with Time-Based Plotting Tools" on page 11-17 11 Plotting Data Choosing and Configuring Plotting Blocks In this section. . . "Sources of Data for Plotting" on page 11-2 "Inserting and Connecting Scope Blocks" on page 11-3 "Connections Among Points in Plots" on page 11-4 "Varying Axis Limits Automatically" on page 11-5 "Caching Data in Scopes" on page 11-6 "Examples Using Scope Blocks" on page 11-6 Sources of Data for Plotting The table below indicates the kinds of data you can plot using various combinations of blocks and parameter values. To view or set the parameters, open the dialog box using the Parameters toolbar button in the plot window. time Scalar signal values without regard to time Two scalar signals (X-Y plot) Attribute vs. time Attribute values without regard to time Two attributes of same entity (X-Y plot) Attribute vs. attribute Block Signal Scope Signal Scope X-Y Signal Scope Attribute Scope Attribute Scope X-Y Attribute Scope Get Attribute block to assign the attribute value to a signal; followed by X-Y Signal Scope X value from = Event time X value from = Index Parameter X value from = Event time X value from = Index 11-2 Choosing and Configuring Plotting Blocks Data Number of entity arrivals per time instant Number of events per time instant Block Instantaneous Entity Counting Scope Instantaneous Event Counting Scope Parameter The Signal Scope and X-Y Signal Scope blocks are appropriate for data arising from discrete-event simulations because the plots can include zero-duration values. That is, the plots can include multiple values of the signal at a given time. By contrast, the Scope block in the Simulink Sources library plots at most one value of the signal at each time. Inserting and Connecting Scope Blocks The scope blocks reside in the SimEvents Sinks library. Block Signal Scope X-Y Signal Scope Attribute Scope X-Y Attribute Scope Instantaneous Entity Counting Scope Instantaneous Event Counting Scope Input Ports One signal input port Two signal input ports One entity input port One entity input port One entity input port One signal input port Port Description Signal representing the data to plot Signals representing the data to plot Entities containing the attribute value to plot Entities containing the attribute values to plot Entities whose arrivals the block counts Signal whose signal-based events or function calls the block counts 11-3 11 Plotting Data The following figure shows some typical arrangements of scope blocks in a model. Notice that the blocks that have entity input ports can have optional entity output ports, and that signal lines can branch whereas entity connection lines cannot. Connections Among Points in Plots You can configure certain scope blocks to determine whether and how it connects the points that it plots. To view or change the parameter settings, open the dialog box using the Parameters toolbar button in the plot window. Setting Plot type = Stair in the block dialog box Sample Plot Vertical line from horizontal axis to point. Also known as a stem plot. Plot type = Stem in the block dialog box 11-4 Choosing and Configuring Plotting Blocks Connection Characteristics Line segment from point to point. Also known as a first-order hold. Setting Plot type = Continuous in the block dialog box Sample Plot No connection with other points or with axis. Also known as a scatter plot. Style > Line > None in the plot window Note If no initial condition, data value, or arriving entity indicates a value to plot at T=0, the plot shows no point at T=0. In this case, the plot does not connect the first plotted point to the T=0 edge of the plot. Varying Axis Limits Automatically Using parameters on the Axes tab of the dialog box of scope blocks, you set the initial limits for the axes of the plot. Also, these parameters let you choose how the block responds when a point does not fit within the current axis limits: · If X value is beyond limit · If Y value is beyond limit Choices for the parameters are in the table. 11-5 11 Plotting Data Option Stretch axis limits Description Maintain one limit while doubling the size of the displayed interval (without changing the size of the containing plot window) Maintain both limits, which means that points outside the limits do not appear Maintain the size of the displayed interval while changing both limits Keep axis limits unchanged Shift axis limits Other operations can still affect axis limits, such as the autoscale, zoom, and pan features. [. . . ] This example uses a Counter Free-Running block inside a subsystem to count the number of times the subsystem is called. (Be aware that the Counter Free-Running block starts counting from zero, not one. ) The discrete-event portion of the simulation involves a D/D/1 queuing system in which the server is never idle for a nonzero period of time. As a result, the #n signal exhibits many zero-duration values, shown in the plot below. 16-32 Zero-Duration Values and Time-Based Blocks The example uses two approaches to try to call the subsystem each time the server's #n signal rises from 0 to 1: · The approach using a Triggered Subsystem is unsuitable because it does not count changes that occur in a time interval of length zero. You can see from the Display block that the triggered subsystem is never called. [. . . ]