If you’re interested in PLC programming, you must know about digital logic and its applications. Digital logic is fundamental when creating electronic devices, and an important aspect of programmable logic controllers (PLCs). An understanding of digital logic lends itself to many different professions, including PLC technicians.
Digital logic is the main logic system that encompasses electronic circuit board design.
When we look at computer operations, we’re also looking at circuits and logic gates. These circuits and logic gates are made up of binary values that are manipulated by digital logic. Without digital logic, we wouldn’t have some of the most important electronic devices we use on a daily basis.
If you’re interested in PLCs and you’d like to learn more about digital logic and its applications, then continue reading.
What is Digital Logic?
Let’s take a moment to expand on our definition of digital logic. Digital logic, or boolean logic, is the set of rules that allow us to make complicated decisions by only using “yes” or “no” questions. It’s the basis of all modern computer systems, making up the most common household items such as calculators, watches, and video games. While this might seem elementary, gaining knowledge in digital logic is a huge advantage to those who are interested in becoming a PLC technician.
Digital logic circuits are broken into two distinct subcategories: combinational and sequential.
Combinational Logic
Combinational logic is also referred to as “time-independent logic,” and is defined by the output being independent of time, relying only on the input that is present. Combinational logic is used in computer circuits, performing Boolean algebra on input signals and on stored data. Other circuits used in computers, such as encoders and decoders, are also made by using combinational logic
Sequential Logic
Sequential logic differs from combinational logic in that it’s output not only depends on the input but the input’s history. Sequential logic utilizes memory, whereas combinational logic does not. This form of logic is used to create “finite-state machines” (FSM), which is a key component to lots of digital circuits. Basically, all circuits use a mix of combinational and sequential logic in order to function.
The Main Components of Digital Logic
We can’t talk about the components of digital logic without first discussing truth tables. Truth tables are used in mathematics, and also help us understand the behaviour of logic gates. They’re a visual representation of how inputs relate to their outputs, showing each possible input combination and the consequential output.
The 7 different logic gates that can be found in a digital logic or Boolean truth table include: “AND,” “OR,” “NAND,” “NOR,” “NOT,” “XNOR” and “XOR.”
These logic gates are small transistor circuits that form broader integrated circuits. Each type of gate has one or two inputs and one output. Basic logic gates are used in tandem with each other to create different computing outcomes, with each of these logic gates having a very specific way of handling the inputs and the output that it produces.
With the “AND” logic gate, both inputs are entirely dependent on each other. With the “OR” logic gate, you only need one of your inputs to be a 1 for the output to also be a 1. The “NOT” gate has an output that is the reverse of the input. For “NAND,” this logic gate works as both an AND gate and a NOT gate (you might have been able to figure this out by the combination of letters). With “NAND,” if the input is at 1, then the output is at 0. Otherwise, the output is at 1.
A “NOR” logic gate works both as an “OR” gate and a “NOT” gate. It first performs the operation of the “OR” gate, followed by the “NOT” gate. An “XNOR” gate has two inputs and one output. If both inputs are 1, the output will be 1. If the inputs are 1 and 0, the output will be 0. You can think of a “XOR” gate as being a kind of either/or situation. You’ll always get an output of 1 if your inputs are a mix of a 1 and a 0. And if you have two of the same inputs, like a 0 and a 0, or a 1 and a 1, then you’ll get a 0 for an output.
“NAND” and “NOR” logic gates are universal gates and can be implemented through any boolean expression without relying on other logic gates. The applications of basic logic gates are endless, as they’re used in circuits like automated watering systems, burglar alarms, and thermostats. There’s no limit to the number of logic gates that can be found in a given electronic device, advancing operations.
Careers and Courses That Use Digital Logic
Now that you have an overview of digital logic, we can talk about the many different careers that use it. Electronic and computer engineers use digital logic on a daily basis in order to perform their jobs, building complex electronic components. PLC technicians require a deep understanding of digital logic in order to design, program, and repair PLCs that are found in the manufacturing industry as well as the service industry.
Other occupations that employ digital logic include assembly language programmers, circuit design engineers, computer repair technicians and digital IC design engineers. Since digital logic is one of the building blocks of all electronic devices, understanding it and gaining hands-on experience with it is a must. There are a wide variety of programs and courses that cover digital logic and its applications, allowing students to gain hands-on experience.
Continue Your Learning
Now that you have an overview of digital logic and how it relates to circuity, you can decide whether or not you want to pursue a career that utilizes it on a daily basis. If you’re at all excited about this fascinating topic, then maybe a future career in PLCs is for you.
George Brown College offers a PLC Technician Training Program that provides hands-on experience and more information about digital logic. Kickstart your career and apply today.
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