This direction is quite easy and requires little components. All you need is a few resistors and PNP transistors. Diagram: I have represented the Arduino RX pin as a diode and resistor just to think ...

For the challenge, I wanted to send data from my computer's real serial port (RS232 9-pin connector). For that, I created an adaptor circuit because the voltages on a computer serial port are ...

Figure 2. The RS232 or DB9 serial cable, no stranger to manufacturers using the Modbus protocol to communicate between PLCs. (Source: cooking hacks) TTL – RS232 Signals. An Arduino is not able to ...