DigiKey Industrial Automation Demo: IO-Link Ball Float

Automation and Control
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The ball float project is a demonstration of industrial control systems with an emphasis on IO-link. It features a Siemens S7-1200 PLC with a PROFINET connection to a SICK IO-Link master which is then connected to three IO-Link enabled devices. Together these elements form an interactive display where the user can adjust the height of a ping pong ball floating in a tube as shown in Figure 1.

This article is part of the DigiKey Field Guide for Industrial Automation

Location: Showcase It → DigiKey Projects
Difficulty: :seedling: Student— difficulty levels explained
Last update: 15 Jun 2026

Figure 1 Image of the ball float project on an A-frame
Figure 1 Image of the ball float project on an A-frame1920×1536 287 KB

Figure 1: Image of the ball float project on an A-frame.

Project Highlights

The section provides a high-level introduction to the technology featured on the DigiKey demo.

  • The user interacts with the project using slide control to control the position of the ball within the tube. The screen capture for the HMI is shown in Figure 2.
  • A fan is used to provide a column of air for the ball. This fan is driven by a Pulse Width Modulation signal from the PLC.
  • The IO-Link driven LED strip highlights the ball position.
  • The user can enter can enter text messages into the Siemens HMI to be displayed on the top mounted text display.

Figure 2: Image of the HMI control window.
Figure 2: Image of the HMI control window.799×478 110 KB

Figure 2: Image of the HMI control window.

Control Algorithm

This project implements a classic Proportional Derivative Integral (PID) control system.

  • The user provides the desired setpoint via the HMI.
  • The distance sensor provides the feedback indicating ball height in the tube.
  • A Siemens designed PID performs the internal calculation
  • The PID drive is sent to the fan which controls ball height.
  • Automatic tuning was used to set the PID control parameters.
  • The HMI displays the input, feedback, and plant drive signals.

Networking

  • IO-Link is used to connect the text display, the distance sensor, and the LED strip. These are connected to the IO link master as ports S2, S4, and S6 respectively

  • The PROFINET protocol is used to communicate between the PLC, HMI, and IO Link master. A unmanaged switch is used for the Ethernet connections.

Featured DigiKey Products

These products define the core architecture of the IO-Link Ball Float demonstration and illustrate how a modern PLC-based system senses, communicates, and responds in real time.

  • Siemens S7-1200 PLC Gen 2 PLC (CPU 1214C): The PLC serves as the central controller for the demonstration. It hosts the PID logic, exchanges data over PROFINET, and coordinates the HMI and IO-Link devices.

    • Latest addition to Siemens S7-1200 family.
    • Expandable with local modules, IO-Link, and distributed I/O such as the ET 200SP
    • Note the quick disconnect terminal blocks for local I/O
    • Native PROFINET
    • Near Field Communication allowing a cell phone to read diagnostic data

  • SICK SIG300 IO-Link master (PROFINET): The SIG300 forms the bridge between the PLC and the smart field devices. It is the key networking element that allows the demo to showcase practical IO-Link integration.

    • PROFINET to IO-Link
    • Three styles of ports including 2-wire Class-A1, 3 wire Class-A2, and high current Class-B (up to 4 A per M12 connector).
    • USB programmed or controlled from PLC
    • IP67

  • SICK W10 Distance Sensor: This sensor provides the feedback signal for the control loop by measuring the ball position within the tube.

    • IO-Link enabled
    • Red laser pointer
    • 50 to 250 mm distance detection
    • Cyclic data transfer to the PLC via the SIG300

  • Banner SD50 Status Display: The SD50 gives the demo an operator-facing output, allowing text and status information to be displayed directly from the control system.

    • IO-Link enabled
    • Cyclic update
    • Change text on the fly

  • E-T-A Solid State Circuit Breaker: The electronics circuit breaker protects the demo’s 24 VDC control system while giving the project a visible, industrial-grade layer of electronic protection.

    • Semiconductor-based current limiting
    • Near instantaneous response (no thermal or magnetic delay)
    • Slide switch adjustable current limit
    • LED status display

Supporting DigiKey TechForum Material

Learn more about the technology by exploring these closely related articles.

Parts List

Project components available from DigiKey:

Technical Contribution to Automate 2026