To use MAX, expand Devices and Interfaces>Ports. Right click on the port you want and select Open VISA Session. Click the Basic I/O tab on top and then either the Write or Read tab. You;ll notice that the deault command is the *IDN? query with a \n character. This is the line feed constant. In your VI, you are not sending any termination character and this is something that is normally required. Try either the line feed or carriage return. You will have to turn on '\' Codes Display for your string control in order to enter the actual control character or use the concatanate string with the constants you'll find on the String palette.
