Siemens/Allen Bradley PLC Product Selection Guide

The short answer is that Siemens is generally superior for complex, data-heavy processing and global standardization, while Allen Bradley remains the king of North American discrete manufacturing due to its ease of use and maintenance.

Choosing between these two automation giants is rarely about specifications alone. It is a strategic decision that affects your hiring, your supply chain, and your long-term maintenance budget. 

In 2025, the gap between them has narrowed in terms of raw speed, but the philosophical divide remains massive. If you are building a machine for a US automotive plant, you use Rockwell (Allen Bradley). If you are shipping a wind turbine to Europe or Asia, you use Siemens.

Here is the no-nonsense breakdown of how these two stacks compare right now.

The Core Difference: Engineering vs. Maintenance

To understand the battle of Allen Bradley vs Siemens, you have to look at who they are building for.

Siemens designs for the engineer. Their controllers, particularly the S7-1500 series, rely on “Data Blocks” and a structured memory approach. It is incredibly powerful if you are a computer scientist or a high-level programmer because you can manipulate data in ways that standard PLCs struggle with. However, this complexity can be a nightmare for a midnight shift technician trying to troubleshoot a stopped conveyor.

Allen Bradley designs for the maintenance team. Their Logix platform uses a tag-based database that is intuitive. You create a tag named “Motor_Start” and you are done. There are no memory addresses to manage. Allen Bradley controls prioritize uptime and quick online edits, allowing technicians to modify logic while the machine is running without crashing the processor.

Software Showdown: TIA Portal vs. Studio 5000

The software is where you will spend 90% of your time, so this matters more than the hardware speed.

Siemens TIA Portal: This is an “all-in-one” environment. You program the PLC, design the HMI screens, and configure the VFD drives, all in one project file.

• The Good: Excellent diagnostics and variables are linked automatically. If you change a tag name in the PLC, it updates in the HMI.
• The Bad: It is heavy. The install size is massive, and it requires significant PC resources. The learning curve is steep.

Rockwell Studio 5000: This is the gold standard for interface design. It is clean, visually open, and forgiving.

• The Good: Online editing is superior. You can see exactly what is happening in the logic with live values that are easy to read.
• The Bad: It is disjointed. You need Studio 5000 for the PLC, FactoryTalk View for the HMI, and Connected Components Workbench for the drives. They don’t always talk to each other seamlessly.

Analyzing Siemens vs Allen Bradley PLC Advantages and Disadvantages

When we look at the raw pros and cons, cost and usability are usually the deciding factors.

Siemens Advantages

• Performance: The S7-1500 processor is a beast. It handles floating-point math and complex loops faster than most competitors.
• Diagnostics: The integrated display on the CPU faceplate allows you to see fault codes without even plugging in a laptop.
• Cost: Hardware is generally 20-30% cheaper for equivalent performance.

Siemens Disadvantages

• Complexity: The strict data typing means you cannot just mix integers and floating points without explicit conversion. It forces you to write cleaner code, but it slows down development.
• US Support: Finding a Siemens expert in rural Ohio is harder than finding a Rockwell guy.

Allen Bradley Advantages

• Market Dominance: In the US, parts are everywhere. You can likely buy a replacement input card from a distributor down the street.
• Legacy Support: They are excellent at supporting older hardware.
• Ease of Use: The learning curve is practically flat compared to Siemens.

Allen Bradley Disadvantages

• Cost: The hardware is expensive.
• Licensing: The annual software support fees can be a major line item in your OpEx budget.

Note: Siemens can assist buyers in choosing between Siemens and Allen Bradley based on budget, compatibility, and specific applications.

The Reality of Pricing

Pricing is the elephant in the room. The Allen Bradley PLC price structure is often referred to as the “Rockwell Tax.” You pay a premium for the ecosystem. A standard CompactLogix processor might cost $3,000, whereas a comparable Siemens S7-1200 might be under $1,000.

However, hardware price is deceptive. If your maintenance team takes three hours to fix a Siemens fault because they don’t understand the software, you just lost more money in downtime than you saved on the hardware. Conversely, if you are an OEM building 1,000 identical machines, the lower hardware cost of Siemens adds up to massive profit margins.

Selection Guide: Making the Call

So, how do you choose?

Go with Allen Bradley if:

1. Location: Your plant is in North America.
2. Staff: Your maintenance team is comfortable with Ladder Logic but not structured text or C++.
3. Application: You are doing high-speed discrete manufacturing (packaging, bottling, assembly).
4. Standardization: Your facility already has Allen Bradley controls installed. Mixing brands in one panel is often a headache.

Go with Siemens if:

1. Location: You are in Europe, Asia, or South America.
2. Application: You are doing process control (chemical, water, energy) or complex data sorting.
3. Budget: You need high performance but have a tight hardware budget.
4. Security: You need advanced integrated security features directly in the CPU.

Note: Siemens can provide side-by-side quotes for the S7 series, CompactLogix, and ControlLogix PLCs for easy comparison and selection.

Siemens SIMATIC S7 PLC

• Manufacturer: Siemens
• Speed: 0.15 μs (S7-200 SMART) to 120 MIPS (S7-800)
• I/O Capacity: Up to 188 points
• Memory: 100 KB–1500 KB work memory
• Comm: PROFINET, Ethernet, RS485, OPC UA, IoT

View Product

Allen‑Bradley 1756 ControlLogix I/O Modules

• Manufacturer: Allen‑Bradley
• Model: 1756 ControlLogix I/O
• Input voltage: 10–30V DC or 79–264V AC
• Max output current: 2A
• Current input: 4–20mA

View Product

Procurement and Supply Chain

In 2025, availability is just as important as features. Both brands have suffered from lead time issues in the past, but supply chains have stabilized. The trick is to avoid single-sourcing your procurement.

When buying Allen Bradley vs Siemens, working with a distributor that handles both can save you significant administrative time. You don’t want to be managing two different vendor portals for one project.

Note: Siemens supports 24-hour quoting, multi-brand integrated procurement, and DDP delivery.

Final Thoughts

Ultimately, there is no “wrong” choice here. Both platforms are world-class. The Siemens vs. Allen-Bradley PLC advantages and disadvantages debate usually ends in a tie technically, but a clear winner emerges operationally based on where your factory is located and who is fixing the machine at 2 AM.