S7-1200 PLC 101: A Step-by-Step Introduction for Beginners

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By the end of this article, you will learn all the basic but practical information you need to know about the popular S7-1200 PLCs.

You will also gain a good understanding of the kinds of industrial applications they are suitable for.

This article is brought to you in partnership with RS, a global omnichannel provider of industrial product and service solutions. Follow this link to learn how they can help bring value and efficiency into every step of your process!

What is an S7-1200 PLC?

Let’s start with the basics of what an S7-1200 PLC is. It’s a type of programmable logic controller manufactured by Siemens, used to control and automate industrial processes.

S7-1200 PLCs

The S7-1200 PLC has two main components: the hardware and the software.

The hardware includes the power supply, central processing unit or CPU, input/output modules, and communication modules.

The software used to program the PLC to perform specific functions based on input signals from sensors and switches is called TIA Portal, which is also developed by Siemens.

S7-1200 CPU models: Industrial applications & comparison

Now let’s discuss the various CPU models available for an S7-1200 PLC and compare them based on their industrial applications.

CPU 1211C

The 1211C is a starter model for the S7-1200 PLCs.

It has less memory and fewer ways to communicate, but it still works well for small and medium automation projects.

Some examples of these projects could be a machine that works by itself which we usually call a stand-alone machine or a system that controls heating, air conditioning, and ventilation in a building (HVAC).

So if you want to create an HVAC system, the 1211C could be a good choice for you.

CPU 1211C applications

CPU 1212C

The next type of S7-1200 PLC that I will talk about is called the 1212C. It’s very similar to the 1211C but has more inputs and outputs.

This makes it a great choice for slightly bigger automation applications, like controlling the temperature of a medium-sized industrial furnace.

CPU 1212C applocation

An industrial furnace is a special device used for heating metal or other materials to very high temperatures in order to shape or alter them. Industrial furnaces are used in a variety of industries, such as metalworking, glassmaking, and ceramics.

The S7-1200 PLCs, especially the 1212C model, are often used to regulate the temperature, pressure, and other parameters inside industrial furnaces.

The 1212C also supports PID control functions, which allows for more precise regulation of temperature and pressure.

CPU 1214C

Moving on to the 1214C model, this is a popular choice for more advanced automation applications, such as moving materials around, running pumps, or managing small processes.

CPU 1214C - Examples

With the 1214C, you can also create PID control functions, just like with the 1212C. PID control is a way to regulate parameters like temperature and pressure in factories.

However, the 1214C can take it a step further with more advanced features for PID control and additional capabilities for managing larger and more complex automation systems.

Additionally, the fancier models of the S7-1200 PLC series can do even more PID control functions!

CPU 1215C

Next, I have CPU 1215C.

This model is a good option for large automation tasks.

By large automation tasks, I mean tasks that usually need high-speed processing and advanced communication capabilities such as complex process control systems, motion control systems, and large material handling systems.

CPU 1215C - Example

One cool thing about this PLC model is that you can use a web browser to control it from far away.

CPU 1217C

The 1217C is similar to the 1215C but it has more inputs and outputs, which means it can handle more complex tasks. It’s also faster, which is important for applications that need to gather data quickly.

One example of an application that needs a faster PLC is high-speed data acquisition. This is when data is collected from a process very quickly.

This is important because the faster the data is collected, the more accurate it is, and the better the process works.

For example, in a high-speed packaging machine, sensors collect data about each package’s size and weight. This data is used to adjust the machine’s settings to make sure it works as well as possible.

CPU 1217C application

If the data is collected too slowly, it won’t be accurate enough to make the right adjustments. This means the machine won’t work as well as it should.

That’s why a faster PLC is needed to collect the data quickly and give real-time feedback to the process.

S7-1200 fail-safe PLCs: Adding safety to control

Let’s talk about S7-1200 fail-safe PLCs which can usually be identified by their yellow colors.

S7-1200 Fail-Safe PLCs

These are special types of PLCs that are designed not only to control machines and equipment but also to keep people safe.

In places like oil rigs or factories where dangerous things can happen, it’s important to have an extra layer of protection to prevent accidents.

For example, let’s say you want to design a control system for an elevator. You could use a regular PLC, like the 1212C, to control the elevator’s movements. But what if the power goes out or something goes wrong?

In that case, you would want to make sure the elevator stops safely. That’s where the 1212FC fail-safe PLC comes in. It has special features that can detect when something is wrong and activate emergency brakes to keep the passengers safe.

In the oil and gas industry, safety is super important because there are a lot of hazards. That’s where fail-safe PLCs are really useful.

They can detect when things like gas leaks happen and automatically shut down equipment, turn on ventilation systems, and warn workers about the danger.

S7-1200 Fail-Safe PLCs - oil and gas industry

One thing to remember is that not all types of S7-1200 PLCs have the fail-safe feature. It’s only available for the 1212C, 1214C, and 1215C models.

What does the letter “C” mean?

You may wonder what the letter C at the end of the S7-1200 PLC models stands for.

The letter C at the end of the S7-1200 PLC models indicates that the PLC has a compact design. A compact design means that the PLC is smaller in size compared to other PLC models.

This makes it easier to fit into smaller spaces or control cabinets. Even though they’re small, compact S7-1200 PLCs usually have built-in inputs and outputs. But, you can always add more input/output modules to them if you need to.

S7-1200 communication ports

In terms of communication ports, all of the S7-1200 PLCs come with PROFINET ports that help them communicate with other machines.

S7-1200 Communication Ports

But sometimes, you may need to use a different type of port like Profibus-DP, I/O Link, or AS-i to make them work with other machines.

For example, imagine you’re working on a project at a factory where you need to control a machine that uses a different port called I/O Link. Unfortunately, your S7-1200 PLC only has the PROFINET port, which doesn’t work with I/O Link.

To fix this problem, you can add a communication module to your S7-1200 PLC.

This module helps the PLC communicate with the machine using the I/O Link port, even though it doesn’t have that port built-in. This makes it easier to control the machine without needing extra hardware or complicated programming.

S7-1200 PLC IO Link communication module


So, to sum it up, in this article, you learned about the S7-1200 PLC made by Siemens.

You also found out about the various types of CPU models and how they are used in different industries, from basic models for simple automation projects to advanced ones that are used for high-speed data acquisition and complex control systems.

In the next article, we will show you how to choose the right S7-1200 PLC for your own project by following a step-by-step guide.

If you need guidance on which products best fit your needs, RS is a great solutions partner who offers application consulting services. The RS Engineering team and Technical Solutions Center are ready to support you with your project needs.

RS Solutions Center

RealPars and RS Americas are offering a limited-time opportunity for a free industrial consultation service available to those located in the US, Canada, or Mexico. Boost productivity, reduce downtime, and drive innovation in your operations.

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