[DM High Voltage]

I am not sure that I am using this form correctly but this was the only post I saw about dashboards. I would like to understand how to get data (a number) from the Java SmartDashboard to the robot. We are running c++ on the robot and I have configured a SmartDashboard which recognises my PutString and PutDouble calls but I can't figure out how to get a value to the GetDouble function from the dashboard.