What is a block diagram?

An introduction to block diagrams

A block diagram is a graphical representation of a system, project, or scenario. It provides a functional view of a system and illustrates how the different elements of that system interlink. Engineers, in particular, use block diagrams to model the elements of a system and understand how they are all connected. But these tools are also helpful in many other use cases.

The blocks that give the block diagram its name represent the different elements within a system. The lines and arrows show the relationships between those blocks. These visual elements provide a high-level, functional overview of the system that is easy to digest and understand.

Creating a block diagrams helps everyone involved in a project understand and visualize exactly what’s needed for something to work as a whole. They create a coherent understanding of the elements required to link together to create the desired end result. In this way, they keep everyone on the team on the same page and working toward a common goal.

When are block diagrams used?

Block diagrams are particularly popular in the engineering world because of the complex, interlinked systems involved in designing and building structures and machines. But that’s not to say you can’t apply block diagrams elsewhere. These versatile diagrams can represent both hardware and software systems.

Engineering

Block diagrams are especially useful for engineering teams, as they depict and describe the principal components and processes that take place within a system. Engineers must understand how systems work before actually building them. And a block diagram provides a perfect overview and synopsis of such a system.

Designing electronics

Electronics have certain processes and steps that need to be fulfilled before they can be properly designed. A block diagram helps to break down the necessary elements when designing electronic equipment. For instance, a block diagram could break down the elements of an audio system. It could show how the power supply unit interacts with the audio mixer and the audio power amplifier to project sound through a loudspeaker.

Hardware and software

Software developers often work in tandem with hardware developers, especially in the realm of engineering and electronics. These systems often have many interlinking elements that are difficult to understand if they aren’t properly mapped out. And that’s where a block diagram becomes so useful.

Mapping processes

A block diagram is a versatile tool that can map out and provide a useful overview of any process or system. The above example of a block diagram shows a team using this diagram to visually represent the components of a website launch process, from the home page to the social and email footers.

Block diagrams vs flowcharts

It’s easy to get confused between block diagrams and flowcharts because they present themselves in similar ways. Both use blocks and symbols to represent the elements or components within a system or process. And both use arrows and lines to represent the relationships between those elements.

Despite looking similar and using many of the same symbols, block diagrams and flowcharts serve different purposes. As shown in the example below, a flowchart presents the flow of information or data in a process. It depicts the sequence of movement between the actors and actions that leads to an eventual end.

Block diagrams, on the other hand, depict the relationships and interactions between components in a functional system, such as an electronic circuit or piece of hardware. They focus on the components and their relationships rather than the specific sequence or steps involved.

Advantages of block diagrams

Block diagrams are useful for people with technical proficiencies, such as engineers or software developers. But they’re also beneficial for team members who may not completely understand the ins and outs of a given system, such as clients or stockholders.

Block diagrams are beneficial, as they:

Help visualize complex systems

While an electronic circuit or piece of hardware may appear simple to some, it often contains a very complex system that allows it to function properly. A block diagram breaks down the essential elements and relationships within such a system to make it more understandable and digestible.

Help non-technical people understand a system or process better

Block diagrams are great communication tools for clients and investors. Breaking down a complex system into an easily understandable visual tool is helpful when explaining a process to non-technical people. Those with limited technical knowledge can better understand what makes each element work and how all the elements need to work together.

Help identify bottlenecks and problems

Mapping out the relationships, interlinks, and general sequence of a system or process can help identify possible issues. Defining the relationships between each block rather than trying to pick apart the system as a whole makes it easier to pinpoint issues in that system.

Are applicable to different use cases and industries

Block diagrams aren’t limited to the technical space. They are versatile diagramming tools you can use in many different industries and scenarios. This makes them useful for a wide range of team members, from project managers to engineers.

Disadvantages of block diagrams

Some possible drawbacks of block diagrams to be aware of are as follows:

The source of energy for the system is not shown

Systems — especially electronic systems and software systems — need an input of power or energy before functioning. Block diagrams often fail to properly present a source of energy or what will give the system the power it needs to work.

They may lack enough details for a proper understanding of a system

Block diagrams aren’t always completely comprehensive. They tend to simplify complex processes, which, for the most part, is a big advantage to engineers and designers. Normally, their technical knowledge allows them to make assumptions that fill in the gaps. However, a block diagram is sometimes too simplified to convey a proper understanding of a given system. It may break down something extremely complex into a simple depiction that isn’t entirely accurate.

Types of block diagrams

Block diagrams can take various forms depending on the nature of the system or process being represented. Here are some common types of block diagrams:

Block definition diagram

The block definition diagram was derived from the UML Class Diagram. This type of block diagram has become a popular tool in machine designing, systems creation, and coding. A block definition diagram is a static diagram depicting a system’s structural elements. This refers to the actual system components and their contents, interfaces, and relationships. This is the standard block diagram.

Functional block diagram

A functional block diagram describes the functions of specific elements and the relationships between those elements.

Functional block diagrams are often used in the engineering and software development industries. They are a great way to visually depict the functions of a system using blocks, connector arrows, and output elements.

System block diagram

A system block diagram represents a large, complex system with interacting components and elements referred to as sub-systems. A system block diagram is typically used to represent the requirements and demands of a system.

Block flow diagram

Above, we covered that flowcharts and block diagrams are similar in how they look but different in what they represent. But what if there was a merger between the two? Well, that’s what a block flow diagram is.

A block flow diagram helps break down the basic structure and process that goes into the functioning of a system. Most of the time, a block flow diagram shows the chronological order of how elements and components interact with one another. This ordered interaction leads to the eventual output that the system seeks to achieve.

Internal block diagram

So far, the types of block diagrams we’ve discussed have focused more on the bigger picture — the overarching processes that occur within a system. But an internal block diagram focuses on the internal procedures that happen within singular elements of a block.

This means the properties, parts, and connections of a singular element are broken down to simplify how that element contributes to the larger system. Applying an internal block diagram to an element is a great way to understand a complex system in depth.

How to create a block diagram

You can create your own block diagram by using Miro’s block diagram maker and following the steps below.

Make sure you understand the system/process

Before you start drafting your diagram, it’s essential to have a clear idea of the system or process you’re trying to depict. If you’re uncertain about the system from the get-go, your final block diagram will be messy and difficult to understand.

List the components of the system

Consider which elements will form the system. Take your time gathering input from the rest of the team, as you don’t want to miss out on any crucial components and have to re-draft at a later stage. Start by brainstorming all the components with your team and ultimately create a comprehensive mind map.

Create a block for each component, and label them

Once you know which components will play a role in the functioning of the system, create a block for each one. It’s a good idea to use UML shapes, like blocks, rectangles, ovals, and diamonds, to represent your system blocks. Put them in the necessary order based on your system.

Add arrows to show how the components are connected, and label them

Once you’ve placed all your elements onto the page, it’s time to connect the ones that interlink using arrows and lines. Label these arrows to show what the relationships between the components entail.

Share and collaborate with your team

Block diagrams can help you get a better understanding of a system. But if you’re working in a team, it’s important to collaborate on the diagram to build a comprehensive picture.

Block diagram best practices

Follow these good practices to create an effective block diagram:

Indicate input and output on the diagram

While block diagrams are mostly used to create a visual representation of a system and the system’s internal components, remember to include an input and output in your diagram. Unlike a flowchart, block diagrams aren’t always drafted with a start and end in mind, but a start and end make for a more effective and comprehensive summary diagram.

Don’t overcomplicate the diagram

Block diagrams are meant to break down a complex system or process into something simple and easy to understand. Don’t allow yourself to get carried away during the diagram drafting stage. Keep it as simple as you can so that it’s easily digestible for all team members and stakeholders.

Use standard labels

Using standard UML symbols and labels will make your block diagram easy to read and understand by everyone, even those with fewer technical skills.

Add color

Don’t be afraid to spruce up your diagram to make it more attractive to look at. Color will hold people’s attention longer, and color-coding different components will make the diagram easier to read.