What are the differences between SIMATIC S7-300 and S7-1500 PLCs?

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.

S7-300ApplicationStandardCPU 312For small-scale applications with moderate requirements on the processing speed.CPU 314For installations with medium requirements on program scope.CPU 315-2 DPMedium to large programming memory with the ability to use SIMATIC engineering tools.CPU 315-2 PN/DPMedium program memory and quantity framework. Integral Profinet interface with 2 ports.CPU 317-2 DPLarge program memory and quantity framework for demanding requirementsCPU 317-2 PN/DPLarge program memory and quantity framework for demanding requirements. Integral Profinet interface with 2 ports.CPU 319-3 PN/DPHigh command processing performance, large program memory and quantity framework for demanding applicationsCompactCPU 312CFor small applications with high requirements in terms of processing powerCPU 313CFor installations with high requirements in terms of processing power and response time.CPU 313C-2 PtPFor installations with high requirements in terms of processing power and response time. Point to point link interface.CPU 313C-2 DPFor installations with high requirements in terms of processing power and response time. Profibus DPCPU 314C-2 PtPFor installations with high requirements in terms of processing power and response time. Point to point link interface.CPU 314C-2 DPFor installations with high requirements in terms of processing power and response time. Profibus DPCPU 314C-2 PN/DPFor machines with high demands of computing power and reaction rate. Combined MPI-PROFIBUS DP-interface onboardFail-SafeCPU 315F-2 DPFailsafe CPU with medium to the large program memory and quantity framework with the ability to use SIMATIC Engineering tools.CPU 315F-2 PN/DPFailsafe CPU with a medium program memory and quantity frameworkCPU 317F-2 DPFailsafe CPU with a large program memory and quantity framework for demanding requirements. Profibus DPCPU 317F-2 PN/DPFailsafe CPU with a large program memory and quantity framework for demanding requirements. Profinet interface.CPU 319F-3 PN/DPFailsafe CPU with highest processing performance, enlarged quantity framework, and enhanced communication possibilities. Profinet Interface

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.

S7-1500ApplicationStandardCPU 1511-1 PNFor small to medium applications, Integrated Profinet I/O interfaceCPU 1513-1 PNFor medium applications. Integrated Profinet I/O interfaceCPU 1515-2 PNFor medium to exceptionally demanding applications. Integrated Profinet I/O interface.CPU 1516-3 PN/DPFor exceptionally demanding applications and additional communication tasks. Integrated Profinet I/O interfaceCPU 1517-3 PN/DPFor demanding applications and additional communication tasks. Additional PROFIBUS DP master interface.CPU 1518-4 PN/DPFor high-performance applications and shortest reaction times. Additional PROFIBUS DP master interface.CompactCPU 1511C-1 PNFor small to medium applications and compact constructions such as in series machine manufacturing. Integrated Profinet I/O interfaceCPU 1512C-1 PNFor medium applications and compact constructions such as in series machine manufacturing. Integrated Profinet I/O interfaceFail-SafeCPU 1511F-1 PNEntry-level CPU for medium fail-safe and standard applications. Integrated Profinet interface for Ethernet and Profinet basic servicesCPU 1513F-1 PNFor medium fail-safe and standard applications. Integrated Profinetinterface for Ethernet and Profinet basic servicesCPU 1515F-2 PNFor medium to large fail-safe and standard applications. Integrated Profinet interface with 2 ports.CPU 1516F-3 PN/DPFor exceptionally demanding fail-safe and standard applications and additional communication tasks. Integrated Profinet.CPU 1518F-4 PN/DPFor high-performance fail-safe and standard applications and shortest reaction times. Integrated Profinet interfaceCPU 1518F-4 PN/DP ODKFor standard and failsafe applications with high demand. Provides decentral structure via Profinet I/O & PROFIBUS DP w/ PROFIsafe

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.

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The RealPars Team