Allen Bradley vs ABB PLCs

Every PLC manufacturer has their own way of presenting their line. And when comparing PLCs from different manufacturers, there is a lot of overlap between manufacturers. Some cover a wide range of automation system sizes with a dizzying array of offerings while others offer seemingly a smaller line that upon closer look covers the same territory as their competitor.

Two of these manufacturers, ABB and Allen Bradley, both offer PLCs with strong feature sets that cover any range of automation needs. Swiss-based ABB offers a wide range of control products including PLCs, HMIs and is well known for its robotics offerings. While US based Allen Bradley is one of the most popular companies for control solutions in the US and the world.

Here is a comparison of the two’s most popular PLC products and features:

Large Control Systems

Both Allen Bradley and ABB offer a full feature PLC line for large control systems. Allen Bradley offers the ControlLogix 5580 and 5570 line. These controllers are used in large factory-wide integrated control systems. They can control a wide range of applications including motion, process and safety. Using the Integrated Architecture Builder software, designers can reduce the time for commissioning a system by allowing I/O, cabling and wiring, motion, and networks through a single interface.

The 5580 is also offered as a safety controller with Allen Bradley’s GuardLogix controller for enhanced safety control and for use within harsh environments. Both come with a single embedded Ethernet port. The Allen Bradley ControlLogix 5570 offers most of the same features as the 5580 but with slightly smaller user memory. The 5570 does not have an embedded EtherNet port but both offer access to multiple I/O options.

The AC500 PLC from ABB is the equivalent model to Allen Bradley’s 5570 and 5580. The strength of the AC500 is in its modularity. This makes the AC500 scalable to large factory applications with complex motion and control requirements. With its decentralized expansion, the AC500 can be customized to fit any large control need. Modules include CPU, I/O modules, terminals, communications modules, field bus interface modules and SD card modules.

These “plug-and-play” modules utilize the ABB Control Builder software, the ABB equivalent to Allen Bradley’s Integrated Architecture Builder software. The AC500 has four EtherNet interfaces and can support different communication protocols, adding flexibility in complex and legacy systems. One key AC500 strength is its built-in interface allowing safety PLC connection. This helps ensure proper monitoring and control of high-risk applications.

Each company has a slightly different approach to process and safety. Allen Bradley offers the ControlLogix 5580 as a process controller but also offers the VersaView 6300 for advanced security and failure control. ABB offers their safety and security features in their modular offerings as a system expansion. Both the ABB AC500 and the Allen Bradley 5580 and 5570 are used for high volume, large operations such as mining, food and beverage, oil and gas and other operations requiring high-volume high-speed control systems to manage motion and process control.

Small Control Systems

For control systems requiring a smaller footprint, both Allen Bradley and ABB offer comparable systems to manage the smaller size. Allen Bradley offers a wide range of models including the CompactLogix 5480 and CompactLogix 5370. For process control, they offer the 5580 and 5380. And for safety, they offer the GuardLogix 5380.

The 5480 is a real-time controller operating on a Windows -based OS. This allows the 5480 to be used in a variety of Industrial Internet of Things (IIoT) applications such as data capture, analytics and predictive algorithms. For those control systems not yet ready for IoT applications, the CompactLogix 5370 relies on Allen Bradley’s robust Integrated Architecture software to allow designers and programmers to reduce time to commission. And for control systems requiring enhanced safety and security, the GuardLogix 5380 enables control systems to manage standard and safety control requirements through the Studio 500 Logix application.

Whereas Allen Bradley delivers safety, process and control through different models within the CompactLogix family, ABB’s AC500eco option relies on its modularity as well as its size. It can be included into the AC500 control system and can be configured as a stand-alone customized solution with additional I/O for standalone or small applications. Programming for the AC500 eco can be done via SD card so there is no need to pull up a programming application, this makes it agile in terms of programming.

Very Small and Simple Control Systems

Some control systems do not require special functionality for either motion or safety. For these applications, Allen Bradley offers the MicroLogix 800 family. They perform simple functions and can communicate through integrated EtherNet/IP, ControlNet or DeviceNet communications. They are used for standalone machines and uses the Connected Components Workbench software. Some members of the MicroLogix 800 family can be used as plug ins on additional Allen Bradley systems. This allows users to increase the functionality of its I/O as well as add processing power to the system. ABB does not offer a specific PLC comparable to this controller, but it is safe to assume that the ABB AC500eco could well serve this function as well.

Divergent Capabilities

While both offer large and small control applications, ABB and Allen Bradley diverge on safety and process control. Allen Bradley offers process and safety as different models within the same series. For example, larger control systems for process control and safety are still considered part of the ControlLogix system, with GuardLogix added as a prefix to those systems needing enhanced safety. Likewise, Allen Bradley uses the CompactLogix name to indicate a system requiring a smaller footprint.

ABB, however, uses a specific model for safety and extreme condition requirements. The AC500-S is ABB’s safety controller and is certified for SIL3 and PL e applications. The AC500-S also uses a separate safety CPU. This is a distinction from Allen Bradley’s size-based Guard offerings as the AC500-S can be used as a controller in both complex and simple control systems. This type of controller is used for lifts, gates, cranes and other heavy lift application.

The same is true of ABB’s approach to extreme conditions. ABB offers the AC500-XC PLC. This ruggedized PLC can withstand a large range of extreme conditions including:

  • High Vibration
  • Hazardous Gasses
  • Extreme Temps (-40-+70° C)
  • Salt

The units are self-contained which eliminates the use of cabinets. The applications where one would expect to see the AC500-XC would be in high wind energy, solar, offshore oil and gas operations, robots in extreme conditions, as well as standard heavy use and heavy weight applications such as hoists and lifts.

ABB General Features

All ABB PLCs utilize ABB’s Automation Builder software. And all models support at least simple motion as a PLC. Because EtherNet is integrated on the CPU module, all ABB PLCs have online access for programming as well as FTP and FTPS server. Max program memory varies due to unit size with the AC500eco at 512kB of program memory, the AC500 at 16MB and the AC500-S and AC500-XC with 1.3 MB. All models have RS485 serial communication capability and all but the AC500eco have RS 232.

Because of the modularity, ABB PLCs can be scaled depending on feature sets. Factors can include basics such as power supply and temperature or environmental conditions. They can also extend to application features such as condition monitoring requirements, various motion configurations, and data logging. They may also factor in application performance and communication bus requirement. This modularity is a key strength of ABB PLCs and allows for the creation of a highly customized control system that fits specific needs.

Allen Bradley General Features

The Allen Bradley line of PLCs is categorized more by size than ABB. For example, the ControlLogix family is more often utilized for large complex factory settings while the CompactLogix is geared more toward midrange. For standalone and simple or no motion controls, Allen Bradley has the MicroLogix PLCs. For ruggedized units, Allen Bradley also offers models with the ArmourLogix name within each sized classification. This is their version of the AC500-XC from ABB.

While Allen Bradley does have expansion modules to increase capability, they are available and limited to that size range only for the most part. This limits Allen Bradley controllers to a size range rather than a customizable configuration as found in ABB PLCs. In ABB, the system is built on the modularity. In Allen Bradley controllers, the modularity is added only after the right sized system is determined.

Allen Bradley also differs in its software across its models as well. The ControlLogix and CompactLogix use the Integrated Architecture software whereas the MicroLogix uses the Connected Components Workbench. Contrast this with the ABB units which all use the Automation Builder Software.

Allen Bradley PLCs also utilize different communication protocol capabilities. The ControlLogix series can use a wide variety of options including EtherNet/IP, ControlNet, DeviceNet, DH+, Remote I/O and SynchLink while the CompactLogix can use EtherNet/IP and a USB client for the 5380 and EtherNet/IP, USB client and DeviceNet on the 5370. All ABB PLCs by contrast allow EtherNet IP from the chosen CPU for the control system.

Both Allen Bradley and ABB offer popular and capable PLCs for almost any control system needs. But their approach, and therefore the selection, will depend upon the system requirements of each user.

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