Hobby Components RS485 Transceiver

Used it to link two microcontrollers about 30 meters apart and it just worked, no glitches even with a couple of sensors sharing the line. The MAX487's low-power mode is a nice touch since I'm running this off a battery. Solid little board for the price.

The MAX487 chip makes this module feel rock solid—I ran a 30-meter cable to a sensor and didn't lose a single byte of data. It's compact enough to tuck into a tight enclosure, and the pinout is clearly labeled, so wiring took me under five minutes.

Finally got this wired up to an Arduino for a garden sensor array and the data comes through clean at over 300 feet. The compact size made it easy to fit inside a small weatherproof box.