Fldigi Running on Microsoft Windows XP, Vista, or Windows 7
This program is required to get operating on digital modes. Follow the recommended settings given below and you should not have any problems.
1. Download the latest version of fldigi from the fldigi download page.
2. Install at least two sets of com0com ports (COM5&15, & COM6&16). Go to  to learn about and install com0com.
3. Install Virtual Audio Cable (VAC). Follow FlexRadio instructions: How to Setup Virtual Audio Cable (VAC) 4.0x with PowerSDR 1.x at 
4. In PowerSDR setup>CAT Control set the CAT settings to COM5, 38400, none, 8, 1, then Enable CAT. Set the PTT control to COM6, check RTS and then Enable PTT. Set ID as: PowerSDR
5. In fldigi>Configure>Operator setup your data
6. In fldigi>Configure>Rig Control>RigCAT setup your data as follows: Check Use RigCAT, Rig description file: PowerSDR.xml (download from fldigi xml archives), Device: COM15, Baud rate: 38400, check RTS/CTS flow control (all other items unchecked), then initialize.
7. In fldigi>Configure>Rig Control>Hardware PTT Check: Use separate serial port PTT (yes, turn that little diamond dot to red), Device: COM16, Check: Use RTS, then Initialize. At this point you should be communicating between PowerSDR and fldigi. If not, shut down fldigi (remember to save the data) and restart. If it still does not work, recheck all settings and restart the computer, restart both programs, and then check for communications and TX/RX control.
8. In fldigi>Configure>Sound Card (Audio Devices) select: Port Audio (yes, that small red diamond again) and set Capture: Virtual Cable 2, and set Playback: Virtual Cable 1.
9. In PowerSDR>Setup>Audio>VAC set Driver: MME, Input:Virtual Cable 1, Output:Virtual Cable 2, Check: Auto Enable (Enable for Digital Modes, Disable for all others), Check:Stereo, Check:Allow PTT to override/bypass VAC for phone.
10. Use Modes DIGL and DIGU, TX Profile:Conventional, TX Gain so that ALC=0dB or less.