If you select '\r' as your termination character, then the command sent will be sent with an appended carriage return, or 0x0D (decimal 13). You can confirm what the actual write buffer is by using NI-Spy, then you can see if the '\r' is being appended to the write buffer. If it looks like the buffer is correct and your instrument is still not responding, you might check the serial settings for the com port; it can be difficult to get those settings correct for serial instruments.
