I have been playing with some wireless modems that are RS232. I was thinking they should should be plug and play with my FTDI cable right? The cable is 5V and the modems are 5V and so are the rx/tx so I dont need a level converter right? I am trying to get them to communicate with the software used to program them with no luck. I swapped the rx/tx lines with no luck there either. Do I need to buy a USB to RS232 converter?