What is the difference between Allen Bradely and Siemens PLCs?
- General Overview:
- Allen-Bradley:
- Market Focus: Predominantly used in the U.S.
- PLC Families: ControlLogix, CompactLogix, MicroLogix.
- Programming: Known for user-friendly programming environments, making it easier to learn and implement.
- Installation: Requires dedicated Allen-Bradley racks and power supplies.
- Communication: Primarily supports North American protocols (Device Net, ControlNet, Ethernet/IP).
- Allen-Bradley:
- Siemens:
- Market Focus: Predominantly used in Europe.
- PLC Families: SIMATIC S7-200, S7-300, S7-400.
- Programming: More complex, requiring a higher level of expertise.
- Installation: Can be powered by any 24V DC power supply and does not require a rack.
- Communication: Primarily supports European protocols (PROFIBUS, MODBUS).
- Siemens:
- Specific Product Comparisons:
Allen-Bradley ControlLogix vs. Siemens S7-400:
- Memory:
- ControlLogix: Ranges from 2MB to 20MB depending on the model (5570 or 5580 series).
- S7-400: Memory ranges significantly with models offering from 96KB to 4MB, with additional memory dedicated to instructions.
- I/O:
- ControlLogix: Modular, chassis-based system supporting distributed I/O with high scalability.
- S7-400: Modular but not chassis-based, with a limit of 21 expansions, supporting up to 16,384 digital I/O and 4,000 analog I/O.
- Communication:
- ControlLogix: Offers extensive communication flexibility, including EtherNet/IP, ControlNet, DeviceNet, and more.
- S7-400: Connects to Industrial Ethernet and PROFIBUS, with limited support for other protocols.
- Safety:
- ControlLogix: Offers embedded safety features with GuardLogix controllers.
- S7-400: Has integrated safety features but was initially reliant on add-on modules.
- Memory:
Allen-Bradley CompactLogix vs. Siemens S7-300:
- Memory:
- CompactLogix: Ranges from 0.6MB to 10MB depending on the model.
- S7-300: Memory ranges from 32KB to 2560KB, with the use of a Micro Tested Memory Card for backup.
- I/O:
- CompactLogix: Designed to support distributed I/O with local and node expansions.
- S7-300: Modular system with a total digital I/O of 1024 and analog I/O of 256.
- Communication:
- CompactLogix: Supports protocols like EtherNet/IP, DeviceNet, and USB client.
- S7-300: Offers a wide range of communication protocols including PROFIBUS and Industrial Ethernet.
- Memory:
Allen-Bradley MicroLogix vs. Siemens S7-200:
- Memory:
- MicroLogix: Memory ranges from 1KB to 10KB for user programs, with additional data logging capabilities.
- S7-200: Memory ranges from 4KB to 16KB, with consistent battery backup across all models.
- I/O:
- MicroLogix: Offers more digital I/O and greater flexibility for analog I/O expansion.
- S7-200: Limited analog I/O through expansion modules, with I/O ranging from 6 In/4 Out to 24 In/16 Out.
- Communication:
- MicroLogix: Offers RS232, DeviceNet, Ethernet/IP, and more, with superior communication flexibility.
- S7-200: Limited to RS-485, with additional support for MODBUS TCP/IP on certain models.
- Memory:
- Key Takeaways:
- User-Friendliness: Allen-Bradley is generally easier to program and debug, making it a better choice for environments where ease of use is paramount.
- Flexibility in Communication: Allen-Bradley offers more flexibility in communication methods, especially in North America. Siemens, while supporting a wide range of protocols, is more focused on European standards.
- Hardware Requirements: Allen-Bradley requires dedicated hardware components, whereas Siemens offers more flexibility in power supply and installation.
- Market Preference: Choose Allen-Bradley for North American projects and Siemens for European projects, or when working with systems already based on Siemens technology.
