Industrial Automation

Moving from Analog to Digital: Why and How?

Scott Kornblue

With the onset of Industry 4.0 and IIoT, it’s easy to assume that most industrial plants are well on their way to digital transformation. While automation, robots and cobots were already being integrated into plants well before 2020, the pandemic brought forth the need to roll out advanced technology and real-time data even faster to maintain production continuity.

 

As part of this transformation, it’s also easy assume that most plants are moving toward digital signals, which are more accurate and versatile than analog signals. From where we stand, however, the industry isn’t quite there yet.

 

Industrial control systems that rely on analog signals haven’t been manufactured in more than two decades, but there are still many of these systems in use—although they’re reaching end of life and will soon be difficult and costly to support in the future. In fact, upkeep may actually cost plants more money over time than converting to a digital system.

 

Because they’re comfortable working with analog signals, some plants have chosen to make them function for as long as they can. But times are changing. Many of the industry’s experienced controls engineers are headed toward retirement. New generations of workers will fill these positions over the next decade, and they’re more likely to put automation and technology at the forefront of industrial processes.

 

We’re already seeing this shift occur in some of the plants we work with: A long-time plant manager retires, and a new plant manager comes in with different ideas. To get buy-in, they present an analysis that compares the “old way” to the “new way.” Once the C-suite—particularly those who control the budget—hears the argument for a digital system and why it will be better than existing analog systems in terms of analytics and automation, the plant will likely start moving in that direction.

 

Analog vs Digital Signals: What’s the Difference?

 

Analog signal is a continuous value that changes over time, such as voltage or pressure. Analog signals involve point-to-point communication instead of multi-point communication: If you have 10 machines, then you’ll need 10 separate systems for analog signal transmission.

 

Because they typically stay on the machine itself, there isn’t much you can do with analog signals. It’s when they’re converted to digital signals that you open the door to cloud analytics, machine learning and pattern identification.

 

To do this, analog signals can be aggregated into a digital IO-Link signal and brought back to the central control system through digital media using one cable instead of 10. The signal can be multiplexed to 10 different cables at the other end, reducing the amount of cable required for communication.

 

With analog signals, there’s little to no redundancy. Because they have only one path to follow, there’s no way to recover when that path isn’t available. Digital signals, however, can use packet switching or circuit switching. While circuit switching means the signal must always follow the same path to get to its destination (left-right-left-right, for example), packet switching is able to “packet” or “chunk” digital signals and can take one of many different paths to get from point A to point B. If one path is congested, then the signal can be routed along a different path, creating redundancy.

 

The Analog-to-Digital Progression

 

The transition from analog to digital starts with smart sensors that can control machines and provide health monitoring. Unlike normal sensors that communicate a single message, smart sensors collect and report on many data points, such as temperature, humidity, speed, weight, waterflow and more. They’re also able to receive data from the control system, which allows for things like parameter adjustments and turning sensors on/off.  

 

The information smart sensors provide can be used to automate plant processes, reduce mistakes and improve quality control. Over time, as more data is collected, it can be combined to make general assessments about trends and maintenance to positively impact and optimize production.

 

The transition from analog to digital doesn’t have to happen all at once, and it doesn’t have to happen overnight. Some companies have implemented digital processes but still use analog signals to monitor relevant machine information, which serves as a middle ground. There are also technologies that convert signals from analog to digital to support your journey toward digital transformation. It may not be a complete digital overhaul, but it’s a step in the right direction.

 

From time to time, analog signals do still play a role in manufacturing environments. As long as sensors and devices send out analog signals, analog signals will be part of a plant’s processes. Many industrial sites are moving toward a mix of the two. Digital signals aren’t necessarily replacing analog in all cases—instead, they’re working alongside them.

 

Even within Belden’s own cable plants, we have legacy technology that’s several decades old. It still works well for specific applications. At some point, however, we know it will become impractical: no longer supportable and difficult to maintain. For now, however, it works, and we focus our attention on other equipment and technology that require a more immediate transition.

 

The shift toward digital is exciting, holding lots of promise for improvements in safety, productivity and cost—but getting there can take time. If you have questions about how to get started, or what your options are when converting analog to digital, let us know. We’ll listen to your situation and help you decide what path is right for your plant.

 

Belden Senior Solution Consultant Manager for Svc and Support, Sylvia Feng, helped me write this blog. She is a tremendous resource who can address any of your digital transformation questions. If you want to know more about this topic, email me (scott.kornblue@belden.com) or Sylvia (Sylvia.Feng@belden.com).