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How CompactRIO Compares to a PLC


In the world of industrial automation and control systems, the choice between different hardware platforms can be a critical decision. Programmable Logic Controllers (PLCs) have long been the workhorse of the industry, but newer technologies like CompactRIO (cRIO) and Programmable Automation Controllers (PAC's) have been gaining ground. In this article, we will explore the differences between CompactRIO and PLC systems to help you make an informed decision for your industrial automation needs.

Before we delve into the comparison, it's essential to understand what CompactRIO and PLC systems are and their primary functions.

Programmable Logic Controller (PLC)

PLC's are specialized industrial computers designed for controlling industrial processes and machinery. They execute control functions based on logic and timing, making them well-suited for applications requiring real-time control and reliability. PLC's are programmed using ladder logic or other programming languages specifically designed for automation. PCL's have been controlling industry and processes for over 50 years, but are limited on their speed and processing power.

Programmable Automation Controllers

Programmable Automation Controllers (PACs) are advanced industrial control systems that combine the real-time capabilities of PLC's with the computational power and flexibility of PCs. PACs are characterized by their ability to handle complex control tasks, high-speed data processing, and custom algorithms, making them ideal for applications where standard PLC's might fall short. PACs provide a versatile platform for designing and implementing sophisticated control strategies and seamlessly integrating with a wide range of sensors and devices. Whether it's complex automation, data-intensive processing, or demanding industrial environments, PACs offer a powerful and adaptable solution for modern control and automation systems.


CompactRIO is a PAC hardware platform developed by National Instruments that combines a real-time microprocessor, a Real-Time Linux OS, and Field-Programmable Gate Array (FPGA) technology. This platform is known for its flexibility and is often used for applications requiring high-speed data acquisition, complex signal processing, and integration with other systems. CompactRIO systems can be programmed using LabVIEW which makes Data Acquisition (DAQ) and computational algorithms very easy for engineers.

Comparison Factors

Now, let's compare CompactRIO and PLC systems across various factors to help you make an informed choice:

Performance Comparison

PLC's are well-known for their reliable real-time capabilities, making them suitable for many industrial applications. CompactRIO, is also a deterministic and reliable real-time controller, but with a PC microprocessor (like an Intel Core Processor) offering significant processing power and flexibility. Furthermore, the cRIO includes an FPGA, which can be programmed with algorithms and logic that execute on a MHz clock iteration, meaning it can make closed loop inputs and outputs literally in nanoseconds. This makes cRIO an excellent choice for applications requiring high-speed data processing and advanced algorithms.


CompactRIO is highly flexible due to its FPGA, which not only allows you to implement custom signal processing and control algorithms, but also enables Reconfigurable I/O (RIO) which refers to the ability to swap modules and modify the I/O of the system without programming.

Programming Environment

PLC's typically use ladder logic or Structured Text, while CompactRIO systems are programmed using LabVIEW or other programming languages. LabVIEW comes with hundreds of engineering and mathematical algorithms and code libraries, which makes industrial and control system applications powerful with minimal programming. The result can be a fast, complex, and powerful software application that can do much more than a PLC.


Both CompactRIO and PLC systems offer a wide range of communication options. However, the cRIO's microprocessor can be particularly advantageous when integrating with industrial devices and standard networks. A CompactRIO can interact with databases, send emails, or write files to a hard-drive or a network. It can also communicate with third-party instrumentation or external devices using serial (like RS232/422/488), ethernet, or other protocols. Yet cRIO is also designed to work with industrial buses such as Modbus, Fieldbus, EtherCAT, DeviceNET, and more. Lastly, with the additional of bespoke modules and interfaces, it can handle custom communication protocols like Fiber Optic or ISM band radio.


CompactRIO systems are compact, as the name suggests, in comparison to a computer or other larger device with similar computing power. Yet they are about the same size and shape as a PLC. Both come in various sizes, and with varying number of module slots, but larger ones can be bulkier.


PLC's are generally considered very cost-effective for simple control applications. CompactRIO, with its advanced processing capabilities, tends to be pricier and are generally better suited for complex control tasks where the cost can more easily be justified by the results. Additionally, cRIO can potentially save costs in the long run by reducing the need for additional hardware or complex workarounds.


In the CompactRIO vs. PLC debate, there's no one-size-fits-all answer. Your choice should depend on the specific requirements of your application.

If you need real-time control, reliability, and simplicity, a PLC may be the right choice.

However, if your application demands high-performance data processing, custom algorithms, and advanced connectivity, CompactRIO can provide the necessary flexibility and power.

Both CompactRIO and PLC's have their strengths and weaknesses, and the right choice will depend on your unique industrial automation needs.

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