Lesson 2 - Principles of Process Control
This lesson explores exactly what process control is and explains why it is important. It examines the various levels within process control systems and identifies the associated equipment. It also takes a detailed look at the various automation communication and control elements.
The Evolution of Control
As technology advances, so do the options for control.
Comparing conventional wiring to a fieldbus
Fieldbus protocols offer great advances in communication.
So, what are the advantages of fieldbus?
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Less wiring is required.
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Each device can send and receive multiple pieces of information. It would even be possible to receive information on multiple parameters from a single device. We can obtain totaliser values from the instrument; with conventional IO, a separate pulse signal would usually be sent to count total flow.
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Intelligent devices can be used, which can be set up on the control system.
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It is possible to set up local or field-based control loops to ensure continuous running if communication to the PLC is lost.
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The signal is fast, and the quality is unaffected by interference (as can be the case with a 4-20 mA signal).
The disadvantages are:
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It is more expensive than conventional, smaller installations.
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The instruments are more expensive, as they have greater capabilities.
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Fieldbus would not work with existing analogue / 4-20 mA power/communications infrastructure (wiring). All new wiring would need to be put in place.
Wireless communication and the Industrial Internet of Things (IIOT)
The world of automation is rapidly incorporating wireless technology. Handheld devices are becoming more powerful and this technology can be used to change the HMI. Processes could be linked to apps on tablets and operators would be able to access the SCADA systems from anywhere, without having to be in front of a screen in a control room.
Even some of the simplest homebrew equipment comes complete with Bluetooth connectivity and a phone app.
The Industrial Internet of Things (IIOT – also referred to as Industry 4.0 or the Fourth Industrial Revolution) has become a buzzword. It refers to the interconnectivity, automation, real-time data, and machine learning that we can harness across industries. As an example, the suppliers of an analytical sensor could have real time information on the performance of every one of their sensors that is deployed, and then use this to increase their equipment’s reliability for everyone involved.
For more details on Industry 4.0, do refer to the following article. Note, this is for illustrative purposes only and is not a recommendation or endorsement of the supplier’s product:
https://industrytoday.com/article/how-industry-4-0-will-effect-the-food-and-beverage-industry/