What do you see in the Slave Debug window? From what you describe, it sounds like the SDR is replying to polls, but not responding to commands. You should be able to see this in the Slave Debug Window. Also, if you look at the Slave Port Setup Window (Click SETUP | RADIO | SLAVE PORT CONFIGURATION), you will see an option to ENABLE POLLING OF THE SLAVE RECEIVER/TRANSCEIVER ... As a temporary test, UNcheck this option and click APPLY. This will turn off the polling of the SDR and temporarily allow you to focus on the commands from Logger32 to set the SDR frequency/mode. Once you have that squared away, you can get fancy. SeventyThree(s).