Difference between PLC, PAC and IPC

PLCs have many advantages compared to previous technology and are rugged and reliable. However, they

have a single microcontroller and therefore limited logic capacity. This makes them unsuitable for complex

applications that require motion control, which can be achieved only by adding separate modules to the PLCs

or by using a hybrid system with one or several PLCs and an industrial PC. As a consequence, PLCs are ideal

for smaller automation projects in which simple tasks are performed.

PACs offer in fact the same advantages of a hybrid system but without the added hardware. They mount two

or more microcontrollers and have a more sophisticated logic system than a PLC. As a result, they can operate

in multiple domains such as motion, discrete and process control using a single platform. They also provide

better integration with SCADA, which allows them to manage complex industry-specific instructions.

Industrial PCs appeared on the market in the 1990s, allowing users to run PLC-style applications on a regular

PC operating system. The first IPCs were not rugged enough to withstand harsh plant environments and their

operating systems had serious stability issues, but more recent versions have tackled these problems and are

now successfully used in larger applications, alone or in combination with one or more PLCs. However, if in the

1990s it seemed that IPCs were about to take over, it is now clear that PACs are leading the field.

Which one is best for you?

PACs combine the functionality and reliability of a PLC with the processing capability of an IPC, which is why

they are now the preferred type of controller in many manufacturing plants. One single PAC can replace several

PLCs or a hybrid system and offer the added advantage of having all applications running in one single controller.

However, the rule of thumb when choosing a controller is that the size of its capabilities should match the size of

your automation project. In other words, there’s no need to invest in a PAC or a hybrid system if your automation

needs can be handled by a traditional PLC. Ultimately, if you choose the appropriate controller for your application’s

size and plan some room for expansion, you will be able to work with it efficiently for decades.

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