VisSim is a visual

block diagram A block diagram is a diagram of a system in which the principal parts or functions are represented by blocks connected by lines that show the relationships of the blocks.

program for simulation of

dynamical system In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in ...

s and

model-based design Model-based design (MBD) is a mathematical and visual method of addressing problems associated with designing complex control, signal processing and communication systems. It is used in many motion control, industrial equipment, aerospace, and aut ...

embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...

s, with its own

visual language A visual language is a system of communication using visual elements. Speech as a means of communication cannot strictly be separated from the whole of human communicative activity which includes the visual and the term 'language' in relation to ...

. It is developed by Visual Solutions of

Westford, Massachusetts Westford is a town in Middlesex County, Massachusetts, United States. The population was at 24,643 at the time of the 2020 Census. History Westford began as 'West Chelmsford', a village in the town of Chelmsford. The village of West Chelmsfor ...

. Visual Solutions was acquired by

Altair Altair is the brightest star in the constellation of Aquila and the twelfth-brightest star in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinised from α Aquilae and abbreviated Alpha Aql ...

in August 2014 and its products have been rebranded as Altair Embed as a part of Altair's Model Based Development Suite. With Embed, you can develop virtual prototypes of dynamic systems. 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 or now Altair Embed uses a graphical data flow paradigm to implement dynamic systems based on differential equations. Version 8 adds interactive

UML The Unified Modeling Language (UML) is a general-purpose, developmental modeling language in the field of software engineering that is intended to provide a standard way to visualize the design of a system. The creation of UML was originally m ...

OMG 2 compliant state chart graphs that are placed in VisSim diagrams. This allows the modeling 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 multidomain simulation and design.Books on wide variety of technical subjects referencing VisSim
on the

Google Books Library Project Google Books (previously known as Google Book Search, Google Print, and by its code-name Project Ocean) is a service from Google Inc. that searches the full text of books and magazines that Google has scanned, converted to text using optical c ...

It includes blocks for arithmetic, Boolean, and

transcendental function In mathematics, a transcendental function is an analytic function that does not satisfy a polynomial equation, in contrast to an algebraic function. In other words, a transcendental function "transcends" algebra in that it cannot be expressed alge ...

s, as well as

digital filter In signal processing, a digital filter is a system that performs mathematical operations on a sampled, discrete-time signal to reduce or enhance certain aspects of that signal. This is in contrast to the other major type of electronic filter, t ...

transfer function In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a mathematical function that theoretically models the system's output for each possible input. They are widely used ...

numerical integration In analysis, numerical integration comprises a broad family of algorithms for calculating the numerical value of a definite integral, and by extension, the term is also sometimes used to describe the numerical solution of differential equations ...

and interactive plotting.''Visual simulation with student VisSim'', by Karen Darnell, 1996, PWS Pub. Co., Boston, The most commonly modeled systems are aeronautical, biological/medical, digital power, electric motor, electrical, hydraulic, mechanical, process, thermal/HVAC and econometric.

Distributing VisSim models

A read-only version of the software
VisSim Viewer
is available free of charge and provides a way for people not licensed to use VisSim to run VisSim models.
on company website This program is intended to allow models to be more widely shared while preserving the model in its published form. The viewer will execute any VisSim model, and only allows changes to block and simulation parameters to illustrate different design scenarios. Sliders and buttons may be activated if included in the model.

Code generation

The "VisSim/C-Code" add-on generates

ANSI C ANSI C, ISO C, and Standard C are successive standards for the C programming language published by the American National Standards Institute (ANSI) and ISO/IEC JTC 1/SC 22/WG 14 of the International Organization for Standardization (ISO) and th ...

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 An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...

. After the behavior 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. VisSim's author served on the X3J11 ANSI C committee and wrote several C compilers, in addition to co-authoring a book on C. This deep understanding of ANSI C, and the nature of the resulting

machine code In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a ve ...

when compiled, is the key to the code generator's efficiency. VisSim can target small

16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mo ...

fixed point systems like the

Texas Instruments Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globa ...

MSP430 The MSP430 is a mixed-signal microcontroller family from Texas Instruments, first introduced on 14 February 1992. Built around a CPU, the MSP430 is designed for low cost and, specifically, low power consumption embedded applications. Applic ...

, 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 kHz on larger 32-bit

floating point processor Floating may refer to: * a type of dental work performed on horse teeth * use of an isolation tank * the guitar-playing technique where chords are sustained rather than scratched * ''Floating'' (play), by Hugh Hughes * Floating (psychological ...

s like the

150 MHz F28335.

Use of model-based development

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

s is becoming widely adopted for production systems because it shortens development cycles for hardware development in the same way that

Model-driven architecture Model Driven Architecture (MDA) is a software design approach for the development of software systems. It provides a set of guidelines for the structuring of specifications, which are expressed as models. Model Driven Architecture is a kind of doma ...

shortens production cycles for software development.Principles of model-driven architecture
Stephen J. Mellor, Addison-Wesley, 2004

Model building Model building is a hobby and career that involves the creation of physical models either from kits or from materials and components acquired by the builder. The kits contain several pieces that need to be assembled in order to make a final mod ...

is a visual way of describing a situation. In an engineering context, instead of writing and solving a system of equations, 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 such as sliders and buttons allow control of

what-if analysis Sensitivity analysis is the study of how the uncertainty in the output of a mathematical model or system (numerical or otherwise) can be divided and allocated to different sources of uncertainty in its inputs. A related practice is uncertainty anal ...

for operator training or controller tuning. Although VisSim was originally designed for use by

control engineer Control engineering or control systems engineering is an engineering discipline that deals with control systems, applying control theory to design equipment and systems with desired behaviors in control environments. The discipline of controls o ...

s, it can be used for any type of mathematical model.

Optional features

CAN bus A Controller Area Network (CAN bus) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for mu ...

packet read and write * Communication system Physical layer simulation (

modulator In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

s, encoders, PLLs,

Costas Loop A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It w ...

BPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at ...

QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at ...

DQPSK Phase-shift keying (PSK) is a digital modulation process which conveys Data (computing), data by changing (modulating) the Phase (waves), phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying ...

QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signa ...

Bit Error Rate In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors. The bit error rate (BER) ...

(BER),

Eye Diagram In telecommunication, an eye pattern, also known as an eye diagram, is an oscilloscope display in which a digital signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizon ...

Viterbi algorithm The Viterbi algorithm is a dynamic programming algorithm for obtaining the maximum a posteriori probability estimate of the most likely sequence of hidden states—called the Viterbi path—that results in a sequence of observed events, especiall ...

, Reed–Solomon, etc.) * C code generation - Generates executable C code directly from the block diagram *

Electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate for ...

simulation library for AC induction, Brushless DC, and

Stepper motor A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any posi ...

s * Embedded system targeting for Texas Instruments C2000 and

ARM Cortex-M The ARM Cortex-M is a group of 32-bit RISC ARM processor cores licensed by Arm Holdings. These cores are optimized for low-cost and energy-efficient integrated circuits, which have been embedded in tens of billions of consumer devices. Though ...

chips. Supports on-chip peripherals like serial ports, CAN, PWM, Quadrature Encoder Pulse (QEP), Event Capture,

Serial Peripheral Interface Bus The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems. The interface was developed by Motorola in the mid-1980s and has become a ...

(SPI),

I²C I2C (Inter-Integrated Circuit, ), alternatively known as I2C or IIC, is a synchronous, multi-controller/multi-target (master/slave), packet switched, single-ended, serial communication bus invented in 1982 by Philips Semiconductors. It is wi ...

Analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide ...

(ADC),

Digital-to-analog converter In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. There are several DAC archit ...

(DAC), and

GPIO A general-purpose input/output (GPIO) is an uncommitted digital signal pin on an integrated circuit or electronic circuit (e.g. MCUs/ MPUs ) board which may be used as an input or output, or both, and is controllable by software. GPIOs have no ...

. * Fixed-point arithmetic blockset for bit-true simulation and code generation * Frequency domain analysis ( Bode plot,

Root locus In control theory and stability theory, root locus analysis is a graphical method for examining how the roots of a system change with variation of a certain system parameter, commonly a gain within a feedback system. This is a technique used as a ...

Nyquist plot In control theory and stability theory, the Nyquist stability criterion or Strecker–Nyquist stability criterion, independently discovered by the German electrical engineer at Siemens in 1930 and the Swedish-American electrical engineer Har ...

) *

Global optimization Global optimization is a branch of applied mathematics and numerical analysis that attempts to find the global minima or maxima of a function or a set of functions on a given set. It is usually described as a minimization problem because the max ...

of system parameters * Neural networks * OPC (

OLE for process control Open Platform Communications (OPC) is a series of standards and specifications for industrial telecommunication. They are based on Object Linking and Embedding (OLE) for process control. An industrial automation task force developed the original st ...

) 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 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such ...

RS-485 RS-485, also known as TIA-485(-A) or EIA-485, is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems. Electrical signaling is balanced, and multipoint systems are supported. The s ...

) 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 In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network ...

(UDP) packet read and write. Allows real-time reading and writing of Ethernet-based UDP packets from the VisSim diagram

References

Texas Instruments MSP430 spotlight article
published in

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operat ...

magazine.
VisSim web site

by Devdas Shetty, Richard A. Kolk, Edition 2, Cengage Learning, 2011, ,
C: A Software Engineering Approach
by Peter A Darnell, Philip E Margolis, 3rd edition, 1996,

External links

A Simulation-Aided Introduction with VisSim/Comm
Digital Transmission Series: Signals and Communication Technology, Guimaraes, Dayan Adionel, 2010,
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, {{DEFAULTSORT:Vissim Mathematical modeling Numerical software Real-time simulation Simulation programming languages Visual programming languages Articles containing video clips