Harris Newsteder is preparing to launch a crowdfunding campaign for the PL1-0, an eight-channel isolated bridge board for connecting industrial programmable logic controller (PLC) sensors running at up to 30V DC to 3.3-5V microcontrollers.
"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," writes Newsteder of the project. "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 one type of sensor and they are usually lacking in quality and documentation. I decided to develop my own PCB."
The PL1-0 offers an isolated interface between any 3.3V or 5V microcontroller, including the ESP32, and industrial high-voltage sensors operating up to 30V DC. The eight sinking outputs can be toggled between 3.3V and 5V pull-up as a single group, while each input can be operated in PNP or NPN modes individually. Each input and output is given a screw terminal along with a field ground, +5V DC and 0V DC. Each sensor can run at different voltage levels, Newsteder explains, providing they share a common ground connection.
Newsteder has confirmed that the PL1-0 board will be released under an open source licence, and that it will launch with a detailed user manual and support for "as long as people continue to use it." More information, and a link to be notified when the crowdfunding campaign goes live, can be found over on Crowd Supply now.
UPDATE: Newsteder has launched the PL1-0 starting at $35 for the board and $42 with a DIN rail mount,