DB25 to DB9 Serial Null Modem Adapter

Adapter board to connect a DB25 Serial Port to a DB9 Serial Port

All signal lines are "crossed", TX goes to RX on the other side and the other way around. The same goes for RTS/CTS and DTR/DSR. This is effectively a Null modem cable, which means you can use this board without any extra cables!

This board is ideal to make a DIY adapter, you can choose to solder a DB25 male or female port, a DB9 male or female port, making it pretty versatile.

The pin headers are to connect DCD lines to their respective DTR pins, this is usually not necessary but if your peripheral requires DCD you can place a jumper in each of the 2 headers

LEDs, current limiting resistors and protection diodes are optional and may be used to visually monitor the TX and RX lines