PLC VS PAC: Similar but not the same.

Programmable Logic Controller (PLC) and Programmable Automation Controller (PAC) are primarily an industrial system that are designed keeping in mind manufacturing environment in a plant. These computers are highly reliable when it comes to gauging the ability to control and monitor industrial processes. PLC’s and PAC’s both utilise protocols and networks such as Ethernet, ControlNET, DeviceNET, and also integrate with software and databases like OPC, and SQL, etc. These systems can be used in combination but, they can be individually characterised. The basic difference lies in the programming interface of the two, making them serve different functions. The PACs are programmed using C or C++, therefore, have an open architecture and incorporate modular design. Whereas, the PLCs have simple program execution. Owing to this, it can scan along with limited memory and discrete Input and Output.

With technology evolving, the difference between the two is seen to be diminishing. However, there is a difference in utility and functionality. Owing to the ease of programming offered by modules, it is easy to attach or detach components from PAC. Moreover, simplified programming makes it capable of monitoring and controlling thousands of input/output (I/O) points. On the other hand, PLCs are wire-based systems and the addition of devices will require additional wiring with them. Since small footprints and compact terminations are hard to wire using conventional methods, the manufacturers are now using prefabricated cable assemblies rather than discrete point-to-point wiring.

PLC’s work well in small-scale automation tasks, like single machine control (on and off using triggers) or smaller scale building automation (lighting, temperature control etc.). However, PLCs are a natural and cost-effective choice. Whereas, PAC’s are targeted towards more complex and larger scale automation architectures. They are particularly suited for multi-domain monitoring and control. Functions such as; advanced process control, motion control, drive control, vision applications and HMI‘s can be run on a single platform, whilst using PC-based software to program, monitor and collect data.

In a nutshell, both PLCs and PACs are advancing in terms of memory capacity and distributed i/o to suit the plants’ need. Moreover, the modern day PLCs and PACs are connected through Industrial internet of things to ensure real-time transmission of data. With the integration of devices connected through IoT, the manufacturing process is even more streamlined and offers better network connectivity.