Power Pins

• VIN - this is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V. The MAX3232E can generate the extra high and low voltages and also safely convert the logic levels needed for RS-232.
• GND - common ground for power and logic.
• V+ - positive voltage rail output from the RS-232 connection. This pin can be used as a reference voltage.
• V- - negative voltage rail output from the RS-232 connection. This pin can be used as a reference voltage.

Low Voltage Side Pins

The low voltage side of the board, labeled LV Side on the board silk, are located on the left side of the board. These pins can interface with your microcontroller UART pins with 3.3V or 5V logic. There are two duplex channels, so you can have both RX and TX plus two flow control pins like RTS and CTS.

• T1 - Logic data input (from UART)
• R1 - Logic data output (to UART)
• T2 - Logic data input (from UART)
• R2 - Logic data output (to UART)

High Voltage Side Pins

The high voltage side of the board, labeled HV Side on the board silk, are located on the right side of the board. These pins can interface with a RS-232 connection, which can require +-6 to +-10V. There are two duplex channels, so you can have both RX and TX plus two flow control pins like RTS and CTS.

• T1 - RS-232 line data output (to remote RS-232 system)
• R1 - RS-232 line data input (from remote RS-232 system)
• T2 - RS-232 line data output (to remote RS-232 system)
• R2 - RS-232 line data input (from remote RS-232 system)