PLCs, PACs

Answers on factory controller upgrades

Nano programmable logic controllers (PLCs) can replace the function of existing equipment and provide Ethernet communication, remote monitoring, e-mail alerts, and integration with supervisory control and data acquisition (SCADA) and other systems.
By Adam Bainbridge January 3, 2020
Courtesy: Eaton

Factory automation controllers are the brains of many operations by guiding automated workflows. Control Engineering spoke with Adam Bainbridge, product manager automation and micro drives, industrial control division, Eaton, for answers about controller trends, challenges, and upgrade benefits.

Control Engineering (CE): What is the important role that controllers play in control systems?

Bainbridge: Programmable logic controllers (PLCs) are microprocessor-based devices used to control industrial processes or machines. They provide advanced functions, including monitoring, control and communications to share data over networks. In industrial environments, PLCs simplify control systems by reducing complexity and improving control system flexibility. The expanding features of modern PLCs can be used to increase process efficiency while providing operators with more data and analytics at their fingertips to simplify anything from maintenance to monitoring and process optimization.

CE: How do the capabilities of modern controllers compare to legacy controllers?

Bainbridge: One of the biggest recent advancements in controllers is the rise of the “nano” PLC. These controllers often use a “brick” form factor, which is a low-profile panel mount modular package compared to a rack mounted solution that has a base module and slots for slice option cards.

Nano PLCs typically are smaller and less powerful than micro PLCs.

The input/output (I/O) count used to be the deciding factor on when a higher class was needed, but this has been eliminated with new expandable designs that make the most of control system scalability. If a control application does not require high-speed position control or precision, or the ability to control multiple devices over industrial communications, a nano controller could save space and cost.

Nano PLCs with expandable designs allow up to 11 add-on modules for up to 188 I/O points to cover a wide variety of applications. Courtesy: Eaton

Nano PLCs with expandable designs allow up to 11 add-on modules for up to 188 I/O points to cover a wide variety of applications. Courtesy: Eaton

Further, intelligent relays were initially launched as simple-to-use relay devices for replacing timers, counters and relays. These devices have evolved alongside PLCs, retaining their easy-to-use programming while gaining functionalities such as process control and mathematical operations. Capabilities have moved from simple stand-alone relays to intelligent devices with capabilities more aligned with controllers.

CE: How do these advanced capabilities benefit control environments?

Bainbridge: Using a nano PLC offers scalability to include simple protections such as temperature monitoring or more advanced functions such as monitoring pump efficiency to check for blockages and send warnings and maintenance reminders to a SCADA system or email the technician directly. Additionally, control system changes are easily accomplished through front panel programming, which eliminates the need to change wiring and minimizes downtime.

Modern PLCs also are commonly paired with software used to program controllers and displays. The software provides circuit diagram input, editing and the diagrams can be displayed in the format desired. An integrated offline simulation tool allows users to test a circuit diagram before commissioning. It supports users who are configuring, programming and defining parameters for all of the intelligent relays.

This next generation of nano PLCs also supports fast Ethernet communication and high flexibility in programming languages. Using Ethernet communication reduces complexity of supporting installed systems by eliminating proprietary programming cables and allowing for connections to all controllers on a network at once. Support for standardized and easy to use programming methods reduces training costs for engineers support for multiple languages gives engineers flexibility to use what they are comfortable with.

CE: How is the technology advancing control system flexibility and scalability?

Bainbridge: The wider voltage ranges of nano PLCs can reduce the number of options and increase the flexibility of a single part number, which makes the product easier to choose, integrate and maintain.

Ultra-compact, intelligent PLCs help advance energy management across nearly all control industries. For example, using a nano PLC as a pump controller can enable users to replace simple proportional integral (PI) controllers. The ability to add 11 expansion modules to one base unit allows for a simpler, more tailored implementation to meet a specific control need. Expansion modules of differing voltages can be mixed and matched with any base unit allowing more flexible and scalable solutions.

CE: Why should controllers be replaced or modernized if they haven’t yet reached end of life?

Bainbridge: Reducing operation costs and increasing efficiency is a challenge faced by all operators and engineers. The choice to upgrade equipment is a balance of investment versus reward.  Many controls engineers are faced with PLCs that have exhausted their capabilities and are driving up costs. By applying modern, nano PLCs, original equipment manufacturers (OEMs) can reduce retrofit times and machine costs while providing more capabilities. These PLCs can replace the function of existing equipment and provide Ethernet communication, remote monitoring, e-mail alerts, and integration with supervisory control and data acquisition (SCADA) software and building management systems (BMS).

Nano PLCs use compact “brick” formfactor for low profile installations with an optional display that can be used to display operational data. Courtesy: Eaton

Nano PLCs use compact “brick” formfactor for low profile installations with an optional display that can be used to display operational data. Courtesy: Eaton

CE:  What are common misconceptions faced when selecting or specifying controllers?

Bainbridge: Misconceptions exist about which type or class of device to use. Operators can use discrete PI controllers, or use device level control such as a variable frequency drive (VFD) to regulate processes. It is a difficult task to balance the cost and capability needed. While discrete components offer reliable simple control, they often lack the configurability or expandability needed to meet changing requirements. Using a PLC reduces these hurdles, and using a modern nano PLC means more capability without increases in cost or complexity.

Adam Bainbridge is product manager automation and micro drives, industrial control division, Eaton. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media, mhoske@cfemedia.com.

MORE ANSWERS

KEYWORDS: Programmable logic controllers, micro PLC

Nano PLCs are smaller with less power and cost than a micro PLC.

Advanced control can be performed in a small, modular brick form factor.

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Adam Bainbridge
Author Bio: Adam Bainbridge is product manager automation and micro drives, industrial control division, Eaton