The Mayfly-Modbus-WingSheild is a hardware adapter to facilitate Modbus communications on the EnviroDIY Mayfly Datalogger, an Arduino-framework microcontroller board specifically designed for environmental Internet of Things (IoT) monitoring applications. Many environmental and industrial sensors use the Modbus RTU logical communication protocol that is typically transmitted over the physical RS-485 serial communication signaling standard.
This adapter board is designed to plug into one of the Mayfly board's 20 pin headers, similar to an Arduino "Shield" but hanging off the side, like a "wing", in order to preserve access to the Mayfly board's other I/O ports. The adapter combines three capabilities:
- RS-485 to TTL serial signal conversion
- Step-up power converter to 5, 9, or 12 VDC, as required by most Modbus-enabled sensors
- Logic-level shifting of the returned digital signals to 3.3V as required by the Mayfly's microcontrolling unit (MCU).
This initial release is for the DIY version of this board, completed on September 27, 2018. It requires having a PCB made using the included Eagle files, then soldering all components onto the PCB by hand. The design is largely based off a prototype fully hand-soldered onto protoboard by @fisherba and @aufdenkampe.