Programmable automation controllers—PACs. You’ve been hearing a lot about them lately. But what are they really, how do they differ from the hardware you’re using now, and why should you be interested?
Let’s take that last question first: Why should you be interested in PACs?
The answer lies in the demands of today’s industrial applications, where interfacing with signals from sensors and actuators is now just the starting point. Advanced control features, network connectivity, integration of remote and distributed subsystems, device interoperability, and enterprise-wide data integration are all requirements you may be called upon to meet.
If there’s a simpler way to meet these requirements, you’d probably like to know about it. And today, PACs seem to be emerging as that simpler way.
How are PACs different?
PACs differ from the hardware you’re probably using now in several ways. In effect, PACs expand the capabilities of hardware you're using now by merging features of more traditional PLC, DCS, and RTU systems, plus adding some capabilities from personal computers PCs.
PLC. Traditional programmable logic controller (PLC) systems provided discrete-logic-based control of input/output (I/O) signals, using ladder logic programming.
DCS. Distributed control system (DCS) technology traditionally provided process control—batch control where product variations are made according to recipes, or continuous process control.
RTU. The traditional remote terminal unit (RTU—also called a remote telemetry unit) provided multiple communication options for monitoring remote assets, such as radio towers or pipelines.
PC. PC-based control traditionally linked an adapter card on a computer to I/O, with custom applications written for control and communication.
Comparing PACs to other Automation Technologies
It's easier to understand and evaluate a new technology if you can see how its capabilities compare with technologies you already know. This chart compares features of a PAC with those of PLCs, DCSs, PCs, and RTUs. Which features will you need for your application?
So, what is a PAC?
It’s generally agreed that industry analyst ARC Advisory Group originated the term PAC. ARC coined the term for two reasons: to help automation hardware users better define their application needs, and to give automation hardware vendors a term to more clearly communicate the capabilities of their products.
ARC defines a PAC as having the following characteristics:
Key Advantages of a PAC
These defining characteristics also describe the key advantages of using PACs in industrial applications:
In summary, PACs now provide the multi-function, multi-domain, multi-tasking, modular, standards-based and efficient control, networking, and communications processor most suited to today’s industrial applications.
More information on PACs
Read the white paper, Understanding PACs in Industrial Automation
Thinking about buying a PAC? See Considerations for Choosing a PAC
See the specs for Opto 22's PAC Project Software Solution
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