Choosing the right PLC platform to specialise in is one of the most important decisions an automation engineer can make. The three dominant players in the UK market are Siemens, Allen Bradley (Rockwell Automation), and ABB. Each has distinct strengths, and understanding their differences can shape your career trajectory.
Siemens: The European Powerhouse
Siemens PLCs, particularly the S7-1200 and S7-1500 series programmed through TIA Portal, dominate European manufacturing. In the UK, Siemens holds a significant market share across automotive, pharmaceutical, and water treatment sectors. The TIA Portal integrates PLC programming, HMI configuration, and drive setup into a single environment, making it a favourite for large-scale projects.
Key strengths of Siemens include excellent PROFINET communication, robust safety integrated systems, and strong presence in process industries. The S7-1500 series offers outstanding processing power and built-in security features that meet modern cybersecurity requirements.
Allen Bradley: The American Standard
Allen Bradley, manufactured by Rockwell Automation, is the dominant platform in North American markets but maintains a strong presence in UK industries with American parent companies. The ControlLogix and CompactLogix platforms, programmed through Studio 5000, are widely used in food and beverage, FMCG, and oil and gas sectors.
Allen Bradley excels in discrete manufacturing applications, offers excellent EtherNet/IP communication, and provides comprehensive integration with Rockwell's broader automation ecosystem including FactoryTalk software. Many multinational companies standardise on Allen Bradley globally.
ABB: The Process Automation Specialist
ABB holds a unique position in the UK market, particularly strong in process industries, power generation, and mining. Their AC500 PLC range and 800xA distributed control system are well-regarded for complex process control applications.
ABB's strength lies in its integration with drives, motors, and robotics. Companies running ABB drives and robots often prefer ABB PLCs for seamless communication and reduced integration complexity.
Market Share and Career Implications
In the UK, Siemens commands roughly 40-45% of the PLC market, followed by Allen Bradley at approximately 25-30%, and ABB at around 10-15%. However, these figures vary significantly by sector. Water utilities overwhelmingly use Siemens, while American-owned food manufacturers typically standardise on Allen Bradley.
For career development, learning Siemens first provides the broadest opportunity base in the UK. Adding Allen Bradley as a second platform significantly increases your marketability. ABB expertise, while more niche, commands premium day rates due to scarcity of qualified engineers.
Programming Differences
Each platform uses IEC 61131-3 programming languages but with distinct implementations. Siemens uses SCL (Structured Control Language) alongside Ladder and Function Block Diagram. Allen Bradley favours Structured Text and Ladder Logic within Studio 5000. ABB supports all five IEC languages through Automation Builder.
The programming philosophy differs too. Siemens encourages object-oriented programming with user-defined types and function blocks. Allen Bradley uses a tag-based approach with Add-On Instructions. Understanding these architectural differences is crucial when switching between platforms.
Which Should You Choose?
If you are starting your automation career in the UK, we recommend beginning with Siemens TIA Portal and S7-1500. The market demand is highest, training resources are abundant, and the platform is increasingly specified in new projects. Add Allen Bradley as your second platform within two to three years, and consider ABB if you specialise in process industries or power generation.
The engineers who command the highest day rates in the UK are those proficient across multiple platforms, capable of integrating different systems within the same facility.