Recently, our regular contributor Steve Meyer spoke to us about the history of motion control and how PC-based control came to be. Here’s what he said. In the Industrial Revolution, machinery was mechanical. Production looms for weaving fabrics and floor coverings were programmed with mechanical memory in the form of hard stops and pins to make sizes […]
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What do programmable automation controller (PAC) add-on modules do?
By Steve Meyer || Programmable automation controllers (PACs) are largely architected as traditional programmable logic controllers (PLCs) to reliably execute control programs. The major difference (from an electronics standpoint) is how PACs have a high-bandwidth backplane that: Allows integration of different architectures Allows additional processors to augment the functionality of the primary PAC. While there’s […]
What do USB data-logging ports do on programmable automation controllers (PACs)?
By Steve Meyer || Data logging (and use of that data later) was once a complicated venture possible only through specialty hardware and applications — often in the form of standalone supervisory control and data acquisition or SCADA systems. Even new software and PC-based systems come at significant cost. In contrast, many of today’s programmable […]
What are DCS, RTU, PLC, and PC functions on programmable automation controllers?
By Steve Meyer || Distributed control systems (DCSs), remote terminal units (RTUs), and programmable logic controllers (PLCs) are control systems with hardware and programming designed to meet the requirements of specific applications. Today’s programmable automation controller (PAC) hardware runs DCS, RTU, PLC, and PC functions as software to replicate the legacy hardware that’s operated in […]
FAQ: Why do so many PC controls integrate HMIs?
By Steve Meyer || Previous generations of control relied on Cathode Ray Tubes (CRTs) for information displays as part of programming terminals. Those unfamiliar with CRTs should read the Wikipedia articles and check Google Images for representations of how the CRT works. It is an interesting part of the history of control. CRTs use high-voltage power supplies […]
FAQ: What is tag naming and the point of defining data types with PAC programming?
By Steve Meyer || Tag naming starts with naming the I/O in a control system. The names might only serve as a bookkeeping convenience for documenting in ladder programs, but in the complex environment of today’s PLC and PAC platforms, tag names are more significant. Tag names can serve as a referent for I/O points in totally […]
FAQ: How to unify distributed I/O with PACs when building new?
By Steve Meyer || A major hardware cost in control systems is that for inputs and outputs. Devising the most suitable arrangement of I/O takes creation of an I/O map. Then grouping I/Os by location helps engineers identify packaging needed to deploy hardware correctly. One caveat: Unless one is using new breeds of design software, mapping and […]
FAQ: Are PACs just for process control or do they work for discrete plant functions?
By Steve Meyer || Programmable automation controllers (PACs) are (by design) a superset of PLCs. Everything that a PLC can do, a PAC can do. Some control tasks done by PACs are possible to do with a PLC but require expensive add-on modules. Conversely, the reliability and ruggedness so common in the physical builds of PLCs is […]
FAQ: How do programmable automation controllers (PACs) handle analog I/O and related controls?
By Steve Meyer || Analog inputs and outputs are generally associated with sensors. These in turn are the key to controlling real-world processes. So depending on the speed and resolution needed to measure events being controlled, analog inputs come in many performance ranges. Common sampling resolutions are 12 to 24 bit, and sampling frequencies range from kilohertz to […]
FAQ: What is the difference between PLCs and programmable controllers (PACs)?
By Steve Meyer || All programmable controllers (PACs) are capable of performing as PLCs but strictly speaking, PLCs can’t work as PACs. That’s because PACs are a superset of PLC-type controls that work when a design needs: • Multiple channels of communication • High data traffic • Coordination with intelligent subsystems Most high-performance PLCs can host intelligent processors […]