The dividing line between microcontroller development board and programmable logic controller (PLC) use cases has become increasingly blurred in recent years, as today’s Arduino hardware is very robust and reliable. But there are still situations in which peace of mind and regulatory standards support the use of a PLC, which is why we launched the Arduino Opta line of micro PLCs. Rob Broomfield, AKA “Metal Fab Man,” took advantage of an Opta to build a set of massive motorized solar panel lifts for a customer.
Broomfield’s project is, essentially, a custom-fabricated steel tube frame with a solar panel mount riding on hardened steel rods and lifted by a winch. With a solar panel in place, the winch must pull up a load of several hundred pounds and so safety was Broomfield’s top priority. He needed to ensure that the system would fail safe, wouldn’t malfunction, and could be put into a secure state when in its top position with all of that potential energy looming.
To achieve that, he used an Opta as a sort of smart relay for the winch motor. It controls the mains power going to the motor and monitors a few inputs as it does. Those inputs include a control pendant with emergency stop switch and proximity sensors at both ends of travel. In addition to the motor, the Opta also controls a solenoid that actuates a locking pin. When the lift reaches its top position and triggers that proximity sensor, the solenoid releases to slide that pin into place. And if the power fails at any time, that pin will remain in place and keep the sliding mount secure.
Update: Broomfield has now shared a video showcasing the completed design. Watch it below for a look at the final product!
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