The PmodRS232 Converter Module Board (the RS232 module) translates voltage from the logic levels used by Digilent system boards to the RS232 voltage used for serial communications.
For datasheets, reference designs, and more,
please visit the Analog Devices wiki.
There are two UART signal pin assignment conventions in use on Digilent products. This product uses the old signal assignment convention. Connecting a product using the old convention with one using the new convention requires the use of a UART Crossover Cable (not included).
for a more detailed explanation.