If you are looking for low-cost, low-power, light-weight way to control a Valon 5009 Dual Frequency Synthesizer module, then the Raspberry Pi is a good way to go. The Pi can control your 5009 using the free Minicom Linux terminal program to send and receive 5009 command line instructions.
The link below gives instructions on how to get and install the Minicom terminal program. http://valontechnology.com/5009users/RPi.htm
Also found on this link are instructions on how to set up a Remote Desktop Connection to control the Pi remotely.