Industry News

Siemens PLC vs Allen Bradley PLC.

News December 06, 2019

Siemens PLC

Allen Bradley PLC

Rockwell and Siemens are two of the biggest companies that are dominating the PLC market. Here is a comparison of these PLC heavyweights.

Allen Bradley PLC Vs Siemens PLC – Which is better for industrial automation?

Right from the time when Dick Morley invented the first Programmable Logic Controller (PLC) in 1969 to till date, PLCs have been of great help to the industrial segment. A PLC which is also known as the industrial computer control system greatly enhances an industrial process while allowing you to easily replicate or change the process. Secondly, it allows you to mix input and output systems for a modular environment.


When it comes to hardware, both these automation tools work the same way and are reliable. They only differ in fewer areas. For instance, when you install the Allen Bradley PLC, you need to connect the Allen Bradley power supply and the Allen Bradley rack as well. Moreover, you need to install additional cards for safety communication ports. Siemens works with any 24V DC power supply. They come with built-in safety communication ports. AB uses American native protocols such as EthernetIP, DeviceNet and ControlNet. Siemens uses European protocols such as ASI and Profibus.

Automation procedure management

Rockwell PLC is easy to configure and manage. The intuitive interface allows users to easily monitor and manage the system. Features such as communication with 3rd party hardware, mass production of code and export/import tags from Excel to scada databases make it popular among endusers. On the other hand, Siemens seems to be complex for regular maintenance staff and require more computer programming background. However, it offers more options to program and customize the process. Siemens PLC offers two safety runtime groups. It means you can divide the infrastructure into two groups and set controller parameters with different priorities and time cycles. This ability allows you to program blocks and download them to the PLC without stopping any process. With Rockwell PLC, this is not possible as it supports only one safety group. Siemens also offers more programming techniques such as FBD, SCL, STL, LAD etc. However, high-end AB systems support function blocks as well as multiple programming techniques.

Support & Pricing

While pricing is not the first aspect to compare, it has significant important as well. The AB Rockwell automation system is expensive when compared with that of Siemens PLC solutions For instance, the Compact GuardLogix which is the least expensive product from AB is still priced at a higher level. Siemens offers standard technical support for free. When it comes to Rockwell, technical support charges are based on the amount of hardware installed.


While both these automation systems are similar in most areas, the difference lies in the software segment. AB is easy to use and manage but offers limited customization options. Siemens is comparatively inexpensive, allows you to program the software to customize different program blocks but requires more computer programming knowledge. Rockwell is more popular in the US while Siemens enjoys an international market.


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