Connecting the RF1100-232 module
The module requires a 5Volt power supply. Connect GND of your power supply to the GND pin on the module and the 5Volt of your power supply to the Vcc pin on the module.
The serial port on the module is a TTL level port. This means it uses 0Volt and 5Volt levels. It also seems to work fine with 3.3Volt levels. DO NOT connect the serial port on the module to a normal COM port that uses RS232 levels! These COM ports use up to +-15V levels and would damage the module!
If you use a USB to serial converter, make sure you are using one with TTL levels. The module also works fine when connected to the TTL level serial port on an Arduino.
The following picture shows the RF1100-232 module connected to a FTDI USB to serial converter. Please note that you need to connect Tx on one side to Rx on the other side and vice-versa.ly