View source for VisSim

{{Short description|Software for simulation of dynamic systems}}
{{About|the visual block diagram language||Vissim (disambiguation){{!}}Vissim}}
{{Advert|date=May 2013}}
{{Infobox programming language
| name = VisSim/Altair Embed
| logo = [[File:Icon of VisSim v7.svg|75px]]
| paradigm = [[Modular programming|Modular]], [[Visual programming language|Visual Programming]], [[Simulation language]]
| developer = Visual Solutions / [[Altair Engineering|Altair]]
| latest release version = Embed 2016
| latest release date = January 2016
| license = [[Proprietary software]]
| website = {{URL|http://www.vissim.com}}, {{URL|https://www.altair.com}}
| caption = ''VisSim Viewer icon''
| year = 1989
| influenced_by = [[C (programming language)|C]], [[MASSCOMP|Laboratory Workbench]], [[Stardent Computer|AVS (Advanced Visualization System)]]
| operating_system = [[Windows]]
| file_ext = .VSM
}}
'''VisSim''' is a visual [[block diagram]] program for the simulation of [[dynamical system]]s and [[model-based design]] of [[embedded system]]s, with its own [[visual programming language|visual language]]. It is developed by Visual Solutions of [[Westford, Massachusetts]]. Visual Solutions was acquired by [[Altair Engineering|Altair]] in August 2014 and its products have been rebranded as Altair Embed as a part of Altair's Model Based Development Suite. With Embed, virtual prototypes of dynamic systems can be developed. Models are built by sliding blocks into the work area and wiring them together with the mouse. Embed automatically converts the control diagrams into C-code ready to be downloaded to the target hardware.

VisSim (now Altair Embed) uses a graphical data flow paradigm to implement dynamic systems, based on differential equations. Version 8 adds interactive [[UML state machine|UML]] [[Object Management Group|OMG]] 2 compliant [[State diagram|state chart graphs]] that are placed in VisSim diagrams, which allows the modelling of state based systems such as startup sequencing of process plants or serial protocol decoding.

==Applications==
VisSim/Altair Embed is used in [[control system]] design and [[digital signal processing]] for multi-domain simulation and design.<ref name="References">[https://books.google.com/books?q=VisSim+Visual+Solutions Books on wide variety of technical subjects referencing VisSim] on the [[Google Books Library Project]]</ref> It includes blocks for arithmetic, boolean, and [[transcendental function]]s, as well as [[digital filter]]s, [[transfer function]]s, [[numerical integration]] and interactive plotting.<ref name="userguide">''Visual simulation with student VisSim'', by Karen Darnell, 1996, PWS Pub. Co., Boston, {{ISBN|0-534-95485-5}}</ref> The most commonly modelled systems are aeronautical, biological/medical, digital power, electric motor, electrical, hydraulic, mechanical, process, thermal/[[Heating, ventilation, and air conditioning|HVAC]] and econometric.<ref name="References"/>

===Distributing VisSim models===
[[File:VisSim screenshot.PNG|left|thumb|VisSim viewer screenshot with sample model]]
A read-only version of the software, [http://www.vissim.com/downloads/demos.html VisSim Viewer], is available free of charge and provides a way for people who do not own a license to use VisSim to run VisSim models.<ref name="Viewer">[http://vissim.com/products/vissim_viewer.html Viewer page] on company website</ref> This program is intended to allow models to be more widely shared while preserving the model in its published form.<ref name="Viewer"/> The viewer can execute any VisSim model, and only changes to block and simulation parameters to illustrate different design scenarios, are allowed. Sliders and buttons may be activated if included in the model.

==Code generation==
The "VisSim/C-Code" add-on generates [[ANSI C]] code for the model, and generates target specific code for on-chip devices like PWM, ADC, encoder, GPIO, I2C etc. This is useful for development of [[embedded systems]]. After the behaviour of the controller has been simulated, C-code can be generated, compiled and run on the target. For debugging, VisSim supports an interactive JTAG linkage, called "Hotlink", that allows interactive gain change and plotting of on-target variables. The VisSim generated code has been called efficient and readable, making it well suited for development of embedded systems.<ref>{{Cite web |url=http://www.akademik.unsri.ac.id/download/journal/files/waset/v47-35.pdf |title=Graphical Environment for Modeling Control Systems in Full Scope Training Simulators |access-date=2010-09-09 |archive-url=https://web.archive.org/web/20110721120159/http://www.akademik.unsri.ac.id/download/journal/files/waset/v47-35.pdf |archive-date=2011-07-21 |url-status=dead }}</ref> VisSim's author served on the X3J11 ANSI C committee and wrote several C compilers, in addition to co-authoring a book on C.<ref>[https://scholar.google.com/scholar?q=Peter+A.+Darnell&hl=en&btnG=Zoeken&lr= Books on C by Peter A. Darnell and Philip E. Margolis]</ref> This deep understanding of ANSI C, and the nature of the resulting [[machine code]] when compiled, is the key to the code generator's efficiency. VisSim can target small [[16-bit]] [[fixed-point arithmetic|fixed point]] systems like the [[Texas Instruments]] [[MSP430]], using only 740 bytes flash and 64 bytes of RAM for a small closed-loop [[Pulse-width modulation]] (PWM) actuated system, as well as allowing very high control sample rates over 500&nbsp;kHz on larger [[32-bit]] [[floating-point processor]]s like the [[Texas Instruments]] 150&nbsp;MHz F28335.

==Use of model-based development==
{{Main article|Model-based design}}
The technique of simulating system performance off-line, and then generating code from the simulation is known as "model-based development". Model-based development for [[embedded system]]s is becoming widely adopted for production systems because it shortens development cycles for hardware development in the same way that [[Model-driven architecture]] shortens production cycles for software development.<ref>[https://books.google.com/books?id=LGzS1uiUa7AC Principles of model-driven architecture], Stephen J. Mellor, Addison-Wesley, 2004</ref>

[[Model building]] is a visual way of describing a situation. In an engineering context, instead of writing and solving a [[system of equations|system of equation]], model building involves using visual "blocks" to solve the problem. The advantage of using models is that in some cases problems which appear difficult if expressed mathematically may be easier to understand when represented pictorially.

VisSim uses a hierarchical composition to create nested block diagrams. A typical model would consist of "virtual plants" composed of various VisSim "layers", combined if necessary with custom blocks written in C or FORTRAN. A virtual controller can be added and tuned to give desired overall system response. [[Graphical control element (software)|Graphical control element]] such as sliders and buttons allow control of [[what-if analysis]] for operator training or controller tuning.

Although VisSim was originally designed for use by [[control engineer]]s, it can be used for any type of mathematical model.

==Optional features==
{| style="width:320px; float:right; border:1px solid #ccc; background:#f9f9f9; font-size:88%; line-height:1.5em;"
| [[File:VisSim-320x240.ogv]]
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|
Screenshots show the simulation of a [[sine]] function in VisSim. Noise is added to the model, then filtered out using a [[Butterworth filter]]. The signal traces of the sine function with noise and filtered noise are first shown together, and then shown in separate windows in the plot block.
|-
| This video size: 50% (320x240 pixels)
|-
| Other size: [[:File:VisSim-640x480.ogv|100% (640x480 pixels)]]
|}

* [[CAN bus]] packet read and write
* Communication system [[Physical layer]] simulation ([[modulator]]s, encoders, [[Phase-locked loop|PLL]]s, [[Costas Loop]], [[BPSK]], [[QPSK]], [[DQPSK]], [[QAM]], [[Bit error rate|Bit Error Rate]] (BER), [[Eye Diagram]], [[Viterbi algorithm]], [[Reed–Solomon error correction|Reed–Solomon]], etc.)
* [[C (programming language)|C]] [[Automatic programming|code generation]] - Generates executable C code directly from the block diagram
* [[Electric motor]] simulation library for AC induction, [[Brushless DC]], and [[Stepper motor]]s
* Embedded system targeting for Texas Instruments [[C2000]] and [[MSP430]], [[ARM Cortex-M]] chips. Supports on-chip peripherals like serial ports, [[Controller area network|CAN]], [[Pulse-width modulation|PWM]], [[Quadrature encoder|Quadrature Encoder Pulse (QEP)]], Event Capture, [[Serial Peripheral Interface Bus]] (SPI), [[I²C]], [[Analog-to-digital converter]] (ADC), [[Digital-to-analog converter]] (DAC), and [[GPIO]].
* [[Fixed-point arithmetic]] blockset for bit-true simulation and code generation
* Frequency domain analysis ([[Bode plot]], [[Root locus]], [[Nyquist plot]])
* [[Global optimization]] of system parameters
* [[Neural network]]s
* OPC ([[OLE for process control]]) client gives read and write of OPC tags for real-time simulation of [[SCADA]]/HMI virtual plants
* Real-time [[analog signal]] and digital I/O under Windows
* Serial ([[RS-232]]/[[RS-485]]) serial data read and write. Allows real-time reading and writing of serial data from the VisSim diagram. It supports pattern matching, string based transmit, and simulated data streams.
* [[User Datagram Protocol]] (UDP) packet read and write. Allows real-time reading and writing of Ethernet-based UDP packets from the VisSim diagram

==See also==
* [[Web based simulation]]
* [[MATLAB]]/[[Simulink]]
* [[20-sim]]
* {{Annotated link|Ngspice}}

==References==
{{Reflist}}
* [http://www.ieeecss.org/columns/October2007/Oct2007VisSimProductSpotlight.pdf Texas Instruments MSP430 spotlight article]{{Dead link|date=July 2018 |bot=InternetArchiveBot |fix-attempted=yes }} published in [[IEEE]] magazine.
* [http://www.vissim.com VisSim web site]
* [https://books.google.com/books?id=_D58QgAACAAJ Mechatronics System Design], by Devdas Shetty, Richard A. Kolk, Edition 2, Cengage Learning, 2011, {{ISBN|143906198X}}, {{ISBN|9781439061985}}
* [https://books.google.com/books?isbn=9780387946757 C: A Software Engineering Approach], by Peter A Darnell, Philip E Margolis, 3rd edition, 1996, {{ISBN|978-0-387-94675-7}}

==External links==
* [https://www.springer.com/engineering/signals/book/978-3-642-01358-4 A Simulation-Aided Introduction with VisSim/Comm] Digital Transmission Series: Signals and Communication Technology, Guimaraes, Dayan Adionel, 2010, {{ISBN|978-3-642-01358-4}}
* [https://books.google.com/books?id=oJk-g-JDREwC&pg=PA972 Hybrid Intelligent Aircraft Landing Controller and Its Hardware Implementation], by Jih-gau Juang and Bo-Shian Lin in Advances in Natural Computation: Second International Conference, ICNC 2006, {{ISBN|978-3-540-45907-1}}

{{Numerical analysis software}}
{{Fractal software}}

{{DEFAULTSORT:Vissim}}
[[Category:Mathematical modeling]]
[[Category:Numerical software]]
[[Category:Real-time simulation]]
[[Category:Simulation programming languages]]
[[Category:Visual programming languages]]
[[Category:Articles containing video clips]]