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Levels of Data Flow Diagrams

If you ask any pro athlete, professional or professional how they achieved their success and they’ll tell you they were able to master a technique. Through determining what habits contributed to success, and which ones didn’t and enhancing their effectiveness, efficiency and efficiency in their work.

However, implementing a procedure into the workplace, department or even a team is different than focusing on your personal procedure. With all the moving components, how do you monitor each part of your business’s procedure and then refine it?

Data flow diagrams are an easy, effective method for companies to comprehend the process, improve it, and then implement new systems or processes. These are visual depictions of the procedure or system, which is why they aid in understanding and modify.

Before we get into the details of the ways that data flow diagrams can aid in the improvement of any of your company’s processes or systems Let’s look at the specifics of what it is.

What exactly is a Data flow Diagram (DFD)?

The data flow diagram (DFD) is visual representation of information flow within the system or process. DFDs aid in understanding the system’s operation or process to identify potential issues as well as improve efficiency. improve processes. They can range from basic overviews, to detailed, granular visualizations of a process system.

DFDs were popular in the 1970s, and remain popular due to their ease of understanding. Visualizing the way a system or process functions can keep people’s attention and communicate complex concepts more effectively than blocks of text, and so DFDs are able to assist everyone understand the system’s operations and logic.

There are two kinds of DFDs that are physical and logical. Logical diagrams show the method of moving data throughout a system. They show where the data originates the source, where it travels and how it is changed and how it finishes in.

Physical diagrams illustrate how to move information throughout a system, for example, how your particular hardware, software employees, files and customers influence the movement of information.

There are physical or logical diagrams to explain the same information flow or combine them to analyze the system or process on an even more detailed scale. However, before you utilize a DFD to analyze the system’s or process’s flow of information, you’ll need to be familiar with the common symbols or notations that explain the flow of information.

Data Flow Diagram symbols

Data Flow Diagram symbols are standard notations such as rectangles, circles or arrows as well as short-text labels that define the process or system’s direction of data flow as well as data inputs, data outputs, storage points, as well as its numerous sub-processes.

There are four main methods of notation that are used for DFDs: Yourdon & De Marco, Gene & Sarson, SSADM and Unified. They all use the identical labels and similar designs to represent the four primary components of the DFD — an external entity process data store, process data flow.

External Entity

External entities, which are also referred to as sources, terminators, actors, or sinks, are a system or process that transmits or receives data from as well as from the system in which it is diagrammed. They’re the source or the destinations for information, therefore they’re typically placed along an edge of the diagram. The symbols for external entities are identical across all models, except for Unified which employs the stick-figure design instead of a circle, rectangle or square.


Process is a process that alters the information and the flow by taking in data, changing it and generating output from it. The process may accomplish this by using computations and employing logic to sort the data or alter the direction of flow. Processes typically begin at the left-hand side on the DFD and conclude on the bottom left in the drawing.

Data Store

The data stores store information that can be used later such as a database of documents in the process of being processed. Data inputs are processed through a process , and finally through a data storage facility, while data outputs flow through the data store, and later through an process.

Data Flow

The data flow describes the route the information of the system travels from external sources through processes and storage of data. With the help of arrows and concise labels The DFD can help you understand the direction of data flow.

Before you begin mapping out diagrams of data flow you have to follow these four guidelines for creating a valid DFD.

1. Each process must contain at minimum one input and an output.

2. Each data store must include at minimum one flow of data in and one flow out.

3. The data stored by a system needs to be processed.

4. Every step within a DFD need to be linked to another data store or process.

Different levels in Data flow Diagrams

DFDs are a variety of things, from basic overviews, to elaborate detailed representations of a process or system with multiple levels, beginning at the level 0. The most commonly used and straightforward DFDs are the level zero DFDs or context diagrams. They’re easy to digest, and provide a high-level overview that show the way information flows throughout an entire system or process meaning that anyone can comprehend the concept.

Level Zero Context Diagram

This DFD level is focused on the high-level systems processes or functions as well as the sources of data that flow from or to them. Diagrams of Level 0, on the other hand, are created to be straightforward, simple diagrams of a procedure or system.

1. Process decomposition

Although level 1 DFDs aren’t necessarily broad overviews of a process or system However, they’re more specific – they breakdown the single processes into smaller subprocesses.

Level 2: Deeper Dives

The next stage of DFDs go deeper into detail , breaking each level 1 process down into subprocesses that are granular.

Level3: Complexity Increasing

The higher numbers of Level 3 DFDs are rare. This is mostly due to the level of detail required, which is not in line with its primary goal of being easy to comprehend.

How to Create an a Data Flow Diagram

Choose a process or system.
Sort related business activities into categories.
Create a context DFD.
Check your work.
Create diagrams for children.
Expand the processes to level 1 DFDs.
Repeat as necessary.

1. Choose a process or system.

Begin by choosing a specific process or system you’d like to study. Although any process or system could be converted into an DFD however, the more complex the process, the more complex the diagram will become and the more difficult to understand. When you can, begin with a simple operation or process that you’re hoping to enhance.

2. Sort related business activities into categories.

Then, you can categorize the actions that are related to this procedure into entities external to the system, including data flow processes and data storage.

Take a look at a restaurant’s food ordering system. Customers are outside entities, the ordering system for food is a procedure that interacts with both the customer and system (which can be both directions) can be described as the flow.

It is also worth noting? The ordering system also functions as an data store, and when drawing the SSADA model, this is drawing it in an oval shape with rounded corners with two lines of horizontal inside , to show its dual purpose.

3. Draw an FD for Context.

It’s time to begin sketching. DFDs can be drawn by hand, with online templates for free or by using browser extensions.

Begin with a simple DFD of Level 0: Begin with your system or process and then create a map of all the essential connection and flow.

4. Check your work.

Before you dive into more complicated DFDs make sure you review the work you’ve done to ensure it’s correct and complete. If you’ve failed to include (or added) the process, entity or flow the next level of DFDs might not be logical and you might be required to begin again.

5. Make child-friendly diagrams.

For each system or process that you have described within the Level 0 DFD Create an entirely new diagram that has its own flow and entities. Then, you can utilize these diagrams as a way to connect processes.

6. Expand the processes to the Level 1. DFDs.

Utilizing your child diagrams, you must map out more specific connections between each of the processes. For the restaurant we’ve discussed it could be a matter of digging deeper into the ordering system as well as its relationship to managers, suppliers customers, as well as the kitchen staff.

7. Repeat as necessary.

Every process, regardless of how big or insignificant — is able to be reimagined into the Level 0 diagram of context and the cycle can start over. Repeat the steps as necessary to produce the number of DFDs as needed or break the process down further to produce the Level 2, 3, etc. DFDs.

Making Your Process More Effective

Although there’s no such thing as an “perfect” Data flow diagrams, regular practice can streamline the process, and give crucial information about what’s working, which isn’t, and how your company can implement improvements that will have the greatest impact.

Your best bet? Make sure you keep simple. Begin by establishing context, then roll connections and then repeat the process as necessary to define important connections, flows, and the various entities within your company.