It doesn't work without sensors

Article#: 00081

Date: 2023-01-15

Author: Radim

Why do we need sensors on the machine?

1. Together with the actuators, sensors ensure the movement functionality of the machine.

2. Sensors measure process variables and are therefore essential for process control.

3. Sensors measure data about how the machine is doing. This data can be used to reduce downtime, improve performance, detect failure, or predict failure.

4. Sensors can monitor operators' work and make sure the operators don't take any wrong steps.

5. We can only visualize, analyze and process the information for which we have source data. And most of the source data comes from sensors. If we have the relevant data, we can quickly assess the cause of the problem on the machine and avoid lengthy discussions and blind speculation.

A variety of sensors has been developed in recent years. It is therefore advisable to consult selection of a suitable sensor with a supplier.

Some possible requirements for sensor selection are mentioned in the Hardware concept article. And what else is there to consider?

Depending on what the sensor's data will be used for, we need to select a sensor with the appropriate measurement range and accuracy.

The accuracy of the measurement data must not be devalued by improper connection, processing and storage. Pay attention to where the bottleneck is or can be. E.g. slow data transmission, limited throughput, interference, insufficient resolution of the analog-to-digital converter, slow data processing, slow or unavailable memory access, insufficient storage space, ...

For data analysis, it is usually necessary to compare the curves of multiple signals. It may also be necessary to have a reference as to what state and position the machine is in. Therefore, it is important to store historical data from most sensors so that we have it available for analysis.

Use the sensor to monitor the condition or quantity that actually interests you. (For example, if a sensor only monitors the condition that the valve is open, we cannot say with 100% certainty when the valve is closed. Or if we're interested in pressure, then we should measure it and not try to derive it from the measured temperature.)

In order to be able to recognize the deteriorating condition of the machine based on the measured signal, it is necessary to be able to compare this with the signal measured on an optimally functioning machine. Therefore, have reference data ready to identify deviations..

What can be the consequences if the sensor no longer works or delivers incorrect data? Do we need redundant sensors?

Choose such sensors that can accurately (absolutely) determine the state and position of the machine after turning on the machine or after a power failure.

The development of sensors has made great progress in recent years. Sensors have also become cheaper. So it makes sense to think about modernizing and making "old" machines more efficient with new sensor posibilities.

© Radim-Automation, 2020–2025. All rights reserved.
Sharing of this article is permitted with proper attribution (link to the original page).

Related previous articles:

• Talk to operators
• Clear signals
• Design considerations for effective HMIS
• Safety relays versus safety PLC
• Knowledge gained from a completed project is priceless
• Machine modularization
• Hardware concept
• A good concept = Complete set of suitable solutions
• Are there also any disadvantages?
• Think critically!
• Design machines with a focus on user's abilities and needs
• Learn from your journey!
• Collect all the requirements and sort them!
• Functional and intuitive HMI
• HMI and PLC applications should grow together
• More than just start and stop
• Safety first!
• Do the right things and do them right!
• Don't make it worse!
• Industrial evolution - Listen to your customers and follow new trends!
• Stay alert!
• Have an expert on hand!
• What does the customer need?
• Don't disappoint your customer!
• Ask questions!
• Focus on target!
• Check the result!
• Keep it simple!
• Development is evolution
• Transparency and reliability
• From an idea to a consistent system

Related next articles:

• Event logger as the very first function implemented in the program
• Diagnostic tools
• PLC network diagram
• Hidden dangers during commissioning

Comment#: 00001

Date: 2023-01-15

User: Radim

"Human error is a contributing factor in most accidents in high-risk environments."
- Technical Article - Design Considerations for Effective Human Machine Interface Systems.
- https://eao.com/downloads/

Comment#: 00002

Date: 2023-01-15

User: Radim

It's always better to have a sensor that checks that the desired position or state has been reached, rather than just waiting for a timer to expire. In real operation, many unpredictable factors can prevent the desired position from being reached. And the machine program would thus incorrectly assume that the position or state of the machine has been reached when the timer expires.

It is better to monitor the position or the state of the machine with the help of a sensor and, when changing to this position or state, to monitor the elapse of the maximum time required and to react accordingly.

Comment#: 00003

Date: 2023-01-16

User: Radim

Similar to when we need to see curves from multiple sensors, we also need to see the history of the current value along with the setpoint value to be able to compare them and analyze the data. Therefore, let's not forget to also save the history of the setpoint in the historical data.

Comment#: 00004

Date: 2023-07-21

User: Radim

"The essential function of the PLC is to receive data from sensors or other field devices; make a decision on what to do with that information based on its programming instructions, for example, to open or close a valve based on fluid levels or direct a robot to pick up an object based on its presence in the work cell; and send the correct signal to the actuator (such as a valve or robot gripper) to perform the task."
- David Greenfield. AutomationWorld (2023). Peer-to-Peer FAQ: Controllers.
- https://www.automationworld.com/control/article/22724233/industrial-controller-technologies

Comment#: 00005

Date: 2023-09-11

User: Radim

Does it make sense to think about digitalization if we don't see any use case?

"If you don't see any practical use case or clear benefit for digitalization in your specific situation, it may not make sense to pursue it blindly. Digitalization should always align with your organization's goals and needs. Here are some considerations:

1. Assess Business Objectives: Start by identifying your organization's objectives and challenges. Digitalization should align with your strategic goals, whether it's improving efficiency, reaching new markets, enhancing customer experiences, or reducing costs.

2. Customer Demands: Consider whether your customers or clients expect or would benefit from digital solutions. If there's no demand for digital services, investing in them may not provide a return on investment.

3. Competitive Landscape: Analyze your competition. If your competitors are effectively utilizing digital technologies to gain a competitive advantage, it might be necessary to explore digitalization to stay relevant.

4. Cost-Benefit Analysis: Conduct a thorough cost-benefit analysis to determine if the potential benefits of digitalization outweigh the costs. If the investment doesn't offer a reasonable return, it might not be justified.

5. Resource Availability: Evaluate whether you have the necessary resources, including financial resources, technical expertise, and staff training, to implement and sustain digital solutions effectively.

6. Future Growth: Consider the scalability of your organization. Even if you don't currently see a clear use case for digitalization, it's essential to think about your organization's future growth and whether digital technologies could play a role in that growth.

7. Technology Trends: Stay informed about industry trends and emerging technologies. While there may not be an immediate use case, technological advancements could create new opportunities down the line.

8. Customer Feedback: Engage with your customers or stakeholders to gather feedback on their needs and preferences. They may provide insights that could uncover potential use cases for digitalization.

9. Pilot Projects: Instead of a full-scale digital transformation, consider starting with smaller pilot projects to test the waters and assess the feasibility and impact of digital solutions in a controlled environment.

10. Consult Experts: Seek advice from digital transformation consultants or experts in your industry. They can provide insights into potential use cases and help you determine if digitalization is appropriate for your organization.

In some cases, it may indeed be the case that digitalization doesn't make sense for your organization at a given time. However, it's essential to regularly revisit this assessment as technology and business landscapes evolve. What might not be relevant today could become essential in the future. Ultimately, the decision to pursue digitalization should be guided by a thorough understanding of your organization's unique needs and circumstances."

- https://chat.openai.com (Does it make sense to think about digitalization if we don't see any use case?)