In this video and article, you will be learning about the differences between the Siemens SIMATIC S7-300 and SIMATIC S7-1500 Advanced series PLCs.

For both systems, a wide range of modules can be used according to the task at hand and a cost-effective stock of spare parts are readily available.

Overview

Released in 2012, the Siemens SIMATIC S7-1500 is the successor of the longstanding Siemens PLC S7-300.

Although they are interchangeable in many situations, the S7-1500 generation integrates the latest and future-proof technologies into an automation system with enhanced system features over the S7-300.

With the engineering system TIA Portal, the common engineering platform for all SIMATIC controllers, the S7-1500 is designed for fast market changes, constantly shorter product life cycles, and increasing cost pressures.

General Specifications

Both the S7-300 and S7-1500 PLCs are similar in shape and size and are built around a modular, expandable design.

CPUs, I/O modules and communication modules may be added as needed to a standard backplane that can be sized to fit your specific project.

Up to 32 expansion modules can be installed with both systems, requiring only a DIN rail mount and backplane.

The S7-1500 has a standard built-in display and keypad that allows for basic configuration and diagnostics without the need for an external screen.

S7-1500 and S7-300 CPU Categories

Both the S7-300 and S7-1500 series PLCs have many different configuration options that allow the optimal CPU to be selected depending on the application.

Both platforms provide several CPU categories including:

– Standard, for typical applications.

– Compact, for applications where space and cost is a concern.

– Fail-Safe, for fail-safe applications.

The following tables give a basic overview of CPU options you can choose although there are many more selections that are not listed.

S7-300 CPU Categories and their Applications

The following table gives a basic overview of S7-300 CPU options you can choose although there are many more selections that are not listed.

S7-1500 CPU Categories and their Applications

The following table gives a basic overview of SIMATIC S7-1500 CPU options you can choose although there are many more selections that are not listed.

SIMATIC S7-1500 Enhanced Processing Performance

The S7-1500 significantly increases performance over the S7-300 with a faster backplane bus, standard Profinet interface, and shorter reaction times.

As a result, the updated Profinet interface provides greater reproducibility and precision in the nanoseconds timeframe.

When programming for slower processes this may not make a noticeable difference in the real world, however, it can be very useful in high-speed applications such as assembly lines.

SIMATIC S7-1500 Profinet Ports

Two Profinet ports come standard on every S7-1500 CPU although you may select additional ports and communication protocols when ordering.

As an added bonus, you are able to configure these ports as a bridge which acts as a mini switch. This can be very convenient when linking devices and interfacing with the PLC in the field.

With S7-300s, the desired number of ports and appropriate communication protocol must be chosen up-front.

For both systems, there are expansion modules you can add after the fact to add extra ports or communication capabilities.

Siemens S7-1500 Lower Cost

Prices between the S7-300 and S7-1500 are very similar between like models.

If cost is a major concern, the S7-1500 compact version provides up to 70% cost savings, as well as 25% space savings compared to the standard CPUs, although some features are limited.

Selecting a Siemens S7 PLC for Your Project

There are several main factors to consider when selecting a PLC for your project; These factors are:

– Application size

– Available space

– Communications protocols

– Processing performance

By following the table provided above or by using the Siemens website, you can select the appropriate PLC for your specific application.

Additional Benefits of S7-1500 Over S7-300

For almost all applications, the S7-1500 can be used where the S7-300 is used. However, the S7-1500 provides many additional benefits over the S7-300.

– A built-in display comes standard, allowing for easy configuration, such as IP addressing, without the need for programming or tools.

– Plain-text diagnostic information is provided to prevent having to look up error codes resulting in reduced troubleshooting and downtime.

– Sufficient memory is provided a standard for any application regardless of industry.

– There’s also a flexible memory card concept that allows you to select the appropriate memory card for varying project sizes.

– You can store up to 32 GB worth of information on the card for project data and documents.  

– There’s a long service life of 50,000 operating hours.

– There’s no loss of system error messages, even when CPU is in STOP mode.

– You get access to all operating data using Office tools and via Web Server.

In cases where expansion or replacement is required on an existing system using S7-300 PLCs, it may be desirable to continue using the S7-300 series to maintain consistency and the ability to use the same spare parts.

Using TIA portal, S7-1500s have the ability to import old Step 7 projects from an S7-300 PLC and convert to the new format.

In conclusion, both the S7-300 and S7-1500 PLCs are capable and proven systems, providing modular, cost-effective, and application-specific solutions to fit your needs.

In the future, Siemens will slowly begin to phase out the S7-300 in favor of the SIMATIC S7-1500.

Eventually, the S7-300s will no longer be supported, although that is still many years away. As of now the added benefits of the S7-1500 offered at a price point similar to the S7-300 make it a no-brainer to go with the updated PLC on your next project.

Thank you so much for reading, watching and adding your voice to this automation conversation.

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