What are the differences between SIMATIC S7-300 and S7-1500 PLCs?
In this video and article, we will compare Siemens S7-300 with S7-1500 series 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.
S7-300 | Application | |
Standard | CPU 312 | For small-scale applications with moderate requirements on the processing speed. |
CPU 314 | For installations with medium requirements on program scope. | |
CPU 315-2 DP | Medium to large programming memory with the ability to use SIMATIC engineering tools. | |
CPU 315-2 PN/DP | Medium program memory and quantity framework. Integral Profinet interface with 2 ports. | |
CPU 317-2 DP | Large program memory and quantity framework for demanding requirements | |
CPU 317-2 PN/DP | Large program memory and quantity framework for demanding requirements. Integral Profinet interface with 2 ports. | |
CPU 319-3 PN/DP | High command processing performance, large program memory and quantity framework for demanding applications | |
Compact | CPU 312C | For small applications with high requirements in terms of processing power |
CPU 313C | For installations with high requirements in terms of processing power and response time. | |
CPU 313C-2 PtP | For installations with high requirements in terms of processing power and response time. Point to point link interface. | |
CPU 313C-2 DP | For installations with high requirements in terms of processing power and response time. Profibus DP | |
CPU 314C-2 PtP | For installations with high requirements in terms of processing power and response time. Point to point link interface. | |
CPU 314C-2 DP | For installations with high requirements in terms of processing power and response time. Profibus DP | |
CPU 314C-2 PN/DP | For machines with high demands of computing power and reaction rate. Combined MPI-PROFIBUS DP-interface onboard | |
Fail-Safe | CPU 315F-2 DP | Failsafe CPU with medium to the large program memory and quantity framework with the ability to use SIMATIC Engineering tools. |
CPU 315F-2 PN/DP | Failsafe CPU with a medium program memory and quantity framework | |
CPU 317F-2 DP | Failsafe CPU with a large program memory and quantity framework for demanding requirements. Profibus DP | |
CPU 317F-2 PN/DP | Failsafe CPU with a large program memory and quantity framework for demanding requirements. Profinet interface. | |
CPU 319F-3 PN/DP | Failsafe 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.
S7-1500 | Application | |
Standard | CPU 1511-1 PN | For small to medium applications, Integrated Profinet I/O interface |
CPU 1513-1 PN | For medium applications. Integrated Profinet I/O interface | |
CPU 1515-2 PN | For medium to exceptionally demanding applications. Integrated Profinet I/O interface. | |
CPU 1516-3 PN/DP | For exceptionally demanding applications and additional communication tasks. Integrated Profinet I/O interface | |
CPU 1517-3 PN/DP | For demanding applications and additional communication tasks. Additional PROFIBUS DP master interface. | |
CPU 1518-4 PN/DP | For high-performance applications and shortest reaction times. Additional PROFIBUS DP master interface. | |
Compact | CPU 1511C-1 PN | For small to medium applications and compact constructions such as in series machine manufacturing. Integrated Profinet I/O interface |
CPU 1512C-1 PN | For medium applications and compact constructions such as in series machine manufacturing. Integrated Profinet I/O interface | |
Fail-Safe | CPU 1511F-1 PN | Entry-level CPU for medium fail-safe and standard applications. Integrated Profinet interface for Ethernet and Profinet basic services |
CPU 1513F-1 PN | For medium fail-safe and standard applications. Integrated Profinetinterface for Ethernet and Profinet basic services | |
CPU 1515F-2 PN | For medium to large fail-safe and standard applications. Integrated Profinet interface with 2 ports. | |
CPU 1516F-3 PN/DP | For exceptionally demanding fail-safe and standard applications and additional communication tasks. Integrated Profinet. | |
CPU 1518F-4 PN/DP | For high-performance fail-safe and standard applications and shortest reaction times. Integrated Profinet interface | |
CPU 1518F-4 PN/DP ODK | For 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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By Nathan Stone
Automation Engineer
Posted on Apr 29, 2019

By Nathan Stone
Posted on Apr 29, 2019
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