PL1-0 Universal Sensor Interface

Safely connect your microcontroller to sourcing and sinking industrial sensors

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The PL1-0 is an 8-channel sensor interface. It safely connects your 3.3 or 5 volt microcontroller to industrial sensors while offering total electrical isolation between the two. It can be used for industrial automation, home automation, or any project where the sensor you need is only available in a high-voltage configuration.

Use Any Sensor

Each input can be individually configured to interface with either a sourcing (PNP) or sinking (NPN) sensor operating at up to +30VDC. This gives you more flexibility in your sensor selection by allowing you to have any combination of PNP and NPN sensors connected to your microcontroller at a time. PNP sensors running at different voltage levels can also be used together as long as they share a common ground connection.

To show you what this looks like, you could have the following sensors connected for your project:

  • INPUT 1 — 12V PNP Inductive Proximity Sensor
  • INPUT 2 —   5V PNP Limit Switch
  • INPUT 3 — 24V NPN Breakline Sensor
  • INPUT 4 — 24V PNP Diffuse Photoelectric Sensor
  • INPUT 5 — 30V NPN Ultrasonic Proximity Sensor
  • INPUT 6 — Not Connected
  • INPUT 7 — Not Connected
  • INPUT 8 — Not Connected

Use Any Controller

The board features sinking outputs which are pulled-up to a selectable 3.3 or 5 volts when the sensor is off. This makes the PL1-0 just as compatible with an Arduino Uno as an ESP32 or a Raspberry Pi.

Technical Specifications

  • Number of Channels: 8
  • Input Specifications
    • Type: Sourcing / Sinking (Selectable)
    • Voltage: 0 - 30 V DC
  • Output Specifications
    • Type: Sinking
    • Voltage: 3.3 V DC / 5.0 V DC (Selectable)
  • Input Lag: 15 μs
  • Power Input: 1 W @ 5 - 30 V DC
  • Isolation Voltage: 1 k V DC @ 1s

Why I Made This

I designed this board out of frustration with the cost and usability of PLCs. So often at my job I wanted to make a simple machine, fixture, or test rig but I didn’t want to pay hundreds of dollars for a PLC with only 6 digital inputs and 6 digital outputs.

An ESP32 is only $7.00 USD, more powerful, and has more interface options than a PLC. Why can’t I use this microcontroller with the rock-solid sensors available to me in industry?

Of course boards that solve this problem do exist but they are limited to only 1 type of sensor and they are usually lacking in quality and documentation.

I decided to develop my own PCB and I can now proudly present it for others on this website.

Documentation and Support

The PL1-0 is completely open-source. All board and schematic files are available for KiCad. It will launch with a complete user manual and I will continue to support it as long as people continue to use it. Any questions regarding this board can be sent to me directly at

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