Send Command, Read Response, Send & Read Buttons

• The Send Command button writes what you have entered in the Command text box to the I/O buffer.
  
  
• The Read Response button reads the response the device places in the I/O buffer.
  
  
• The Send & Read button writes to the I/O buffer and then reads the response from the I/O buffer.

In the following example (screen capture), the command *IDN? was sent to a Keysight PA2203A Power Analyzer using Send & Read: