When working on automation equipment, you often run into this question:

The PLC is already handling control, so why do I still need an industrial computer? And if I do need one, should I choose ARM or X86?‌

In reality, an industrial computer and a PLC are not mutually exclusive options.

In many projects, the PLC takes charge of low-level real-time control, such as managing motors, cylinders, valves and sensors; the industrial computer handles tasks that PLCs are not designed for, including data acquisition, protocol conversion, SCADA, databases, remote maintenance, cloud communication, and more complex edge computing.

So before making your selection, it is recommended not to look at the CPU first. Instead, clarify exactly what the industrial computer will do in the system.

1. If You Only Need to Collect PLC Data, You Don't Need a High-Performance X86

This is one of the most common requirements today.

For example, a packaging machine is already equipped with a Siemens PLC, which controls all the machine's operations. Now the manufacturer wants to add remote monitoring to upload equipment running status, production output and alarm information to a server.

In this scenario, the industrial computer primarily performs this workflow:

PLC → Data Acquisition → Local Processing → MQTT/OPC UA → MES, SCADA or Cloud Platform‌

Tasks like these do not necessarily require an X86 system.

An ARM industrial PC for PLC is usually more than sufficient, and it is easier to control power consumption, footprint and overall cost.

Take the USR-EG528 for example. It uses a quad-core Cortex-A53 processor, runs Ubuntu, and comes with built-in WukongEdge and Node-RED. It can connect to field devices through interfaces like Ethernet and RS485, and supports PLCs or industrial communication protocols for Siemens, Mitsubishi, Omron, Delta, Fatek, Modbus and more.

Therefore, if your requirements are limited to:
PLC data acquisition, Modbus RTU/TCP conversion, OPC UA, MQTT upload, remote equipment monitoring and simple edge logic, you can prioritize ‌ARM industrial PC models like the EG528‌.

There is no need to deploy a high-performance Core i5 industrial computer just to collect data from a few PLCs.

2. If the Industrial Computer Itself Needs to Run PLC Runtime, Focus on the Software

The second type of requirement is completely different.

Some equipment manufacturers want to reduce the number of hardware components in the cabinet, and integrate the original setup of:

PLC + IoT Gateway + Industrial PC‌

into a single device.

At this point, the industrial computer is no longer just "connecting to the PLC" — it also needs to take on part of the PLC control functionality itself.

The most critical selection indicator then becomes:

Does it support PLC Runtime?‌

The USR-EG628, for instance, runs Linux Ubuntu natively, has OpenPLC built in, complies with the IEC 61131-3 standard, and supports five PLC programming languages: LD, FBD, SFC, IL and ST.

It also provides RS485, RS232, CAN, Ethernet and USB interfaces, and supports extended I/O. For equipment that does not require the extremely high real-time performance of a traditional PLC, this PLC industrial computer can handle data acquisition, control, protocol conversion and cloud communication all at the same time.

PUSR's official documentation cites a production line application case: the EG628 collects PLC signals through extended digital inputs, then controls servo equipment via analog outputs, while coordinating production line operations and synchronizing data to the cloud. The official case states that this setup improved production efficiency by 30%.

This scenario clearly illustrates one key point:

An industrial computer does not have to be just the upper-level host for a PLC. It can also act as an intermediate layer between the PLC and edge control.‌

3. If You Need Windows, CODESYS or Traditional Industrial Software, Prioritize X86

If your project already has a mature software environment, your selection approach needs to change again.

For example, if the original equipment programs were developed for Windows, and engineers still need to run CODESYS, LabVIEW, databases, traditional SCADA or other software that can only operate stably in an X86 environment.

In this case, there is no need to force a migration to ARM just to cut a small amount of hardware cost.

Choosing an x86 industrial PC directly will make things far simpler.

The PUSR USR-EC100, EC300 and EC500 series are built on the X86 architecture, support both Windows and Linux, and official documentation explicitly lists compatibility with industrial software like LabVIEW and CODESYS as a core application direction for this line.

The EC100, for example, is configured with an Intel Celeron J6412, 8GB RAM, dual Gigabit Ethernet ports, 2 RS232/RS485 ports and 4 USB 3.0 ports, making it well suited for traditional equipment HMI, data acquisition, and running Windows-based industrial software.

If your software workload increases further, you can then move up to the EC300 or EC500.

Here is a very simple rule of thumb:

If your project's software ecosystem is built around Windows/X86, prioritize preserving that existing ecosystem instead of redeveloping an entire system for ARM.‌

The costs of re-adapting drivers, PLC communication libraries, databases and HMI programs are almost always higher than the price difference between different industrial computer models.

4. When the Number of PLCs Increases, Check Interfaces First, Not the CPU

This is another scenario where it is very easy to make the wrong choice:

You start with just one PLC, then gradually add several more PLCs, followed by variable frequency drives, meters, barcode scanners and other devices — until you find that your original industrial PC with PLC can no longer keep up.

Many people's first reaction is that the CPU performance is insufficient.

In reality, the far more common problem on site is ‌insufficient interfaces or an unreasonable network structure‌.

For example, if you need to connect all of the following at the same time:

2 Ethernet PLCs
3 RS485 meters
1 CAN device
An MES server
A remote maintenance network

You should first count the number of Ethernet, RS485, RS232, CAN and USB ports required.

The USR-EG628 provides 2 RS485 ports, 1 RS232 port, 1 CAN port and dual Ethernet ports, and also supports extended I/O. It can perform millisecond-level data acquisition for serial and network PLCs, process the data locally, and then upload it to the platform via MQTT or other protocols.

If you need to run Windows software while connecting to even more networks and peripherals, you should turn to x86 industrial PC models like the EC300 and EC500.

Therefore, when selecting an industrial computer for a PLC project, it is recommended to first draw the simplest possible wiring diagram.

List every single connected device, and mark down:

Ethernet, RS485, RS232, CAN, DI, DO, USB.‌

Once you have counted all required ports, you can then select the hardware.

This method is far more effective than directly comparing CPU specifications.

5. If You Also Need a Touchscreen On Site, You Can Consider a Panel PC Directly

Many pieces of equipment have a third requirement:

PLC + Industrial PC + HMI.‌

For example, engineers need the PLC to control the machine, but also need to view operating status, parameters and alarms right on the front of the equipment.

Traditional solutions often require three separate sets of hardware: PLC, Industrial PC and HMI.

If the on-site computing tasks are not overly complex, you can consider combining the industrial PC and HMI into one unit.

The USR-SH800, for example, is built on an ARM Cortex-A55 platform, integrates a 10.1-inch touchscreen, runs Ubuntu, and supports Node-RED, Docker, edge computing and local configuration.

In terms of interfaces, it provides 2×RS485, 2×RS232, 2×Ethernet and 2×USB ports, so it can connect directly to PLCs and other field devices.

For equipment manufacturers, the biggest value of this type of solution is not that "the screen is more advanced", but that it ‌reduces the number of devices, wiring requirements and installation space‌.

This is especially practical for small automation equipment, HVAC systems, packaging machines and equipment control cabinets — often far more useful than simply boosting CPU performance.

6. You Can Select Directly Using This PLC Project Reference Table

This table is not sorted by "performance from low to high", but by ‌task type‌.

This is the far more reasonable selection method for industrial computers in PLC projects.

7. In the End, You Only Need to Remember Four Questions

If you are currently choosing an industrial PC for a PLC setup, you can ask your engineers these four questions directly.

First: Will the industrial computer only "connect to the PLC", or will it "replace part of the PLC"?‌

If you only need to read PLC data, an ARM industrial computer like the EG528 is usually sufficient. If you also need to run PLC Runtime, you can further consider the EG628.

Second: What software will be running on it?‌

For edge applications like Ubuntu, Node-RED, Docker, MQTT and OPC UA, you can prioritize ARM. If you already have Windows, CODESYS or traditional X86 industrial software, prioritize the EC series.

Third: How many devices need to be connected?‌

Count the number of Ethernet, RS485, RS232, CAN, USB and I/O ports first, then select the model.

Fourth: Do you need a screen on site?‌

If you also need to add an HMI, you can consider an Industrial Panel PC like the SH800, which combines display, edge computing and PLC data acquisition in a single unit.

The relationship between industrial computers and PLCs is not complicated.

PLCs excel at deterministic equipment control, while industrial computers excel at data processing, networking, protocol conversion, software execution and edge computing.‌

A truly suitable solution is not to use the highest-spec industrial computer to replace the PLC, but to clearly divide the responsibilities between the two based on your tasks.

If the PLC is already controlling the equipment stably, let it keep handling the control work; let the industrial PC take charge of data acquisition, SCADA, protocol conversion and networking.

If your project truly needs the integration of soft PLC, edge control and equipment networking, then choose an industrial computing platform with PLC Runtime.

The industrial computer you select this way will almost always align far better with the actual project requirements than simply comparing ARM, X86 or CPU clock speeds.