Report on MultiSim.

MultiSim, an industry standard circuit design and testing software suite. Looking at the suitability of the software suite through a series of evaluating exercises is beneficial in demonstrating my understanding of how MultiSim works. I have identified 4 keys areas that I believe are key to critically reviewing the software: Project Environment Initialisation and Settings, Component Library Control, Custom Part and Symbol Creation and Error Analysis and rectification.

It is quite common that the modern electronic engineer would be working on problems that can be scaled into projects with multiple components, MultiSim does not dissatisfy the user and allows projects, the project initialisation (or creation of a new project space) is very simple and can be accessed in the following way:

Figure 1- Context Menu for Setting up a new Project

We can see from the menu that there are number of different options available to the user, specifically at the initialisation stage we are concerned with the creation of a new project, however existing projects can also be opened. When creating a new project, you are presented with the following dialogue, which presents us with the typical fields and settings one would expect.

Figure 2- Project Creation Dialogue

The project name being the desired name for the project and then two save locations, one for backups and one for the projects default save directory. These two being common amongst CAD software.

It is also worth mentioning version control at this stage, within any kind of project work, version control is of great benefit to the user. From my investigation the version control system employed by MultiSim is one that works on the GIT paradigm. Allowing for branches, merges and forks of projects. This enables teams of engineers to work on the same project.

Text Box: Figure 3 - Project File TreeOnce you have created a project, the project is displayed in a file tree to the left of the screen providing you with easy access to all the files that you would need access to. The project name forming the parent of the tree directory and then various folders for your schematics, PCB layouts, simulations, reports and documents. Right clicking allows you to add pre-existing files.

As mentioned in my opening statement of intent, and why I now highlight further, the MultiSim boasts an industry standard Component Library, that is quite massive at 28000 individual industry components (Multisim 14.0 Base Components, n.d.). As you would expect they are organised into a database solution, which with an intuitively designed front end allows brilliant access to the standard components.


 

An overview of the components interface gives us the perfect start for discussion:

Figure 4 - Component Library Overview

 

Text Box: Figure 5 - Component Library, Component List and DetailsThe first look at the component library can be quite intimidating. Which does not exemplify my previous statement about the interface being intuitively designed. However, when we break it down into its constituent parts you can begin to understand my thinking.

Taking this subsection of the of the components library we can easily see a list of the components, their names, and a small visual aid memoir of the components footprint plus a note about the purpose of the component. You can also ascertain greater detail on the selected component, by viewing a detailed report via the button called �Detail Report�.

Addressing the obvious issue of 28000 components leads me to discuss the two methods in which you can narrow your search of the database:


 

Figure 6 - Component Library Search Bar

The small box at the top of the component list is a perfect place for you to search for components that you know the name of (or other important detail, such as capacity, resistance etc.) as you type the list of components shortens.

Using the search bar (detailed above) in conjunction with the component family tree:

Text Box: Figure 7 - Component Library Group Selector

Selecting a component group from the drop down menu and then further honing your search by selecting a family, you can reduce the number of components that are displayed to you in the components list. If you find that there is a further need to simplify your search results, then you can use the search bar.

Finally, in discussion about library control I want to draw your attention to the Database dropdown:

Figure 8- Component Library Database Selector

Automatically the standard `Master Database` is selected, this is the list of components that come as standard with your version of MultiSim. However, we can see two further options, the first being the corporate database; This is especially useful if you are working within a company that produces its own electrical components and these are then stored on a central database, not only can this database be accessed from a local connection (your desktop computer) but it can also be on a networked location, a disadvantage of this is that you are required to have some kind of computing and networking knowledge to be able to set it up.

Leading on from this is the user database, which is local to your machine, this is a database of components that you have either added yourself or you have created yourself (discussed further later in this report).

Databases created in this fashion (fourth normal form relational database systems) are great for storing large amounts of data such as the components library and is often employed within software packaged of this kind.


 

 

Possibly one of the most technical and difficult parts of this report is the explanations surrounding the creation of custom components and is certainly not a task that should be undertaken lightly. There are 8 stages in creating a component, which Nation Instruments have cleverly devised a software wizard to guide the user through. This wizard can be accessed from the tools menu:

Figure 9 - Context Menu Component Wizard Initialisation

The 8 stages of the wizard are as follows (Ni.com, 2016):

1.       Initial Component Information

a.       In this first stage, you assign basic details about your component, name description, creators name and its type (Analogue or Digital).

2.       Footprint and Package Information

a.       Next you enter information that can be found on the components datasheet, often you will find that footprints (the physical specification of the component) can be taken from another component that would found in the Master Database.

3.       Symbol Information

a.       National Instruments, in their tutorial advise that at this stage you use a default symbol from the master component library, but have provided a symbol editing tool if necessary, furthermore they advise at this stage to create both an ANSI and DIN symbol.

4.       Pin Parameters

a.       At this section of the wizard you can set whether a pin is used for an input or an output. You can also exclude the pin from ERC (electrical rules check (more on this later)) for unconnected pins etc.

5.       Link Symbol and Layout Footprint

a.       Moving on in the tutorial we now map the symbol pins to the footprint pins on the PCB, it is recommended to follow the data sheet closely at this stage.

6.       Simulation Model

a.       This stage is somewhat complicated and should be approached carefully. There are some limiting factors here, especially if the designer of the component is not a programmer or has programming experience. This is the stage where we add the code that simulate the component in MultiSim. Some manufacturers of components provide SPICE scripts that can be downloaded and copied in. However, for a bespoke component that is being made the user will be required to create a simulation SPICE model script from scratch.

7.       Link Symbol Pins to Simulation Model

a.       In the penultimate stage we map the symbol pins to the simulation model nodes (sections of the SPICE script) this then completes the technical creation of the custom component.

8.       Save to Database

a.       Finally, we then save the component to our User Database under an appropriate category.

Figure 10 - Analysis Overview

MultiSim offers a wide breadth of simulations that can be used to analyse a circuit. Not only this but a variety of probes:

Text Box: Figure 11 - Probe and Virtual Device Context MenuThese probes and virtual tools can be used to analyse circuit designs or gate logic.

A sensible engineer will of course have done calculations by hand first to use as a benchmark on which the results of simulations can be tested against.

When considering for example the timing of when a capacitor is fully charged to capacity and begins to conduct � we can use the Oscilloscope to map the current flow next to the voltage.If this capacitor discharging is of import to another part of the circuit and specifically its timing, then having empirical evidence from the oscilloscope helps us to rectify the any errors that are occurring.��

A further and more basic examples of MultiSim�s error rectification methods are when circuits have been constructed that are missing vital components, such as a power source or a grounding.

Figure 12 - Error message pop up, no power source


Figure 13 - Error message pop up, Not grounded

In conclusion, MultiSim is an industry standard E-CAD package that has a plethora of features of great benefit to the end user, I have no issue in stating that it is my opinion though that there could be some refinement to make the end users� experience better. Whilst I have not covered in detail the user interfaces of all the features of MultiSim, I feel it worth mentioning now that the interface does feel somewhat dated and tired (as if designed in the early part of the first decade of the 21st century); whilst this does not impact on the overall quality of the software and nor does it render the software fit for purpose, it does hamper the overall user experience. I have to be critical of the experience of creating a custom component, whilst I cannot offer any suggestions that would improve the experience. It seemed somewhat laborious following the tutorial that is provided in the help documentation, which could be both a negative aspect of the overall experience or a reflection on how well the help documentation is written. Furthering my points on negative aspects of the software I have discovered that a number of issues arise from the users of high definition displays (2160p (which I employ)) which prevent traces being scaled properly (on the oscilloscope).

Notwithstanding the flaws there are some incalculable positive aspects of the software package. I am personally fond of the component library and the way in which you can search and find with ease the component you are looking for and in conjunction with this, whilst I do not like the overall experience of creating a new component, it is very positive that you can create or import new components that may not be available.

In addition to this, I am neutral on the project environment, this is a feature that should be included in all industry software, be that CAD, Software IDE�s or PLC simulators.

 

References

Education Edition Help File. (2015). 14th ed. National Instruments Corporation.

Instruments, N. (n.d.). NI MultiSim. National Instruments Electronics Workbench Group.

Multisim 14.0 Base Components. (n.d.). 1st ed. [ebook] Available at: http://download.ni.com/pub/devzone/tut/base_multisim_14.pdf [Accessed 15 Apr. 2016].

Ni.com. (2016). Creating a Custom Component in NI Multisim - National Instruments. [online] Available at: http://www.ni.com/tutorial/3173/en/ [Accessed 16 Apr. 2016].