Lesson 1: Signal Towers

One of the most important considerations when designing a workcell for automated factories is how humans working alongside these machines will stay safe. Signal towers are used in these systems to communicate the status of a machine back to the humans in the surrounding area. This allows those people to then make decisions about how they can remain safe given the status of the workcell.

In this Lesson, you will learn: 

• What a signal tower is.
• How signal towers provide visual indicators of a machine's status.
• The colors on a signal tower and what they communicate.
• The purpose of the Signal Tower on the CTE Workcell.

At the end of this Lesson, you will discuss what you learned as you answer questions in your engineering notebook. 

Signal Towers in Industrial Manufacturing

What is a Signal Tower?

A signal tower, also known as a stack light or indicator light, is a visual signaling device used in industrial manufacturing. These towers are installed on machines to provide quick, easy-to-understand visual cues about the status of the equipment. They are an essential part of modern manufacturing environments, ensuring that operators and maintenance staff can quickly identify issues, monitor processes, and maintain safety.

Signal towers use different colored lights to indicate various statuses of a machine. By glancing at the signal tower, workers can understand if a machine is running smoothly, if there are warnings to pay attention to, or if there’s a critical failure that needs immediate attention. This system helps to improve communication, reduce downtime, and increase overall efficiency.

Industry Standard Signal Tower Colors

Signal towers follow a standardized color scheme to ensure consistency across different machines and industries. Note that not all colors are used on every signal tower. Signal towers at minimum include red and green and often include yellow as well. Watch the video below to see an example of a signal tower in an industrial setting, blinking yellow to show its status. 

Below are the five standard colors and their meanings that will also apply to the Signal Tower used with the CTE Workcell:

• Red: Indicates a serious issue that needs immediate attention. Red lights represent an emergency or controlled stop or other failure conditions.
• Yellow: Represents warnings, such as over-temperature or over-pressure conditions. Yellow lights alert operators to potential problems that could become serious if not addressed.
• Green: Shows normal machine or process operation. A green light means everything is working as expected.
• Blue: Used to indicate some sort of user intervention needed. Blue signals that there may be impending maintenance needs (not warnings or serious conditions), or the workcell may need assistance with identifying an unknown object or refilling raw materials.
• White: This is user-defined and can be customized for specific conditions on a particular machine depending on the needs of the industry and machines.

Signal Tower on the CTE Workcell

The Signal Tower on your CTE Workcell build is included to indicate the status of the Workcell to you and other group members as you simulate real world industry conditions. This helps you to: 

• Identify operational status: Understand if the Workcell is running normally or if there are issues.
• Improve safety awareness: See how signal towers contribute to a safer working environment.

Check Your Understanding

Before beginning the next Lesson, ensure that you understand the concepts in this Lesson by answering the questions in the document below in your engineering notebook.

Check Your Understanding questions > (Google Doc / .docx / .pdf)

Select Next > to learn about industrial robotics safety mechanisms.