Add-on board with four different serial interfaces for the Arduino-compatible universal AVR board Platino. The board has room for a real RS-232 port, an RS-485/DMX512 port, MIDI input and output, and a bus for SPI, I2C, 1-Wire, software serial, etc. with signal levels from 1.2V to 5V. Together with a fully-assembled Platino board (equipped with an ATmega1284P-PU microcontroller and the Serial Bus Tester software 130409-11), this add-on board allows the user to send and receive fully customizable data over a serial bus, either as a reference source, or as a test receiver/transmitter. The board has been described in detail in the March/April 2018 edition of Elektor Magazine.