State of external reference via remote control

Question

I have switched to an external reference frequency.

How can I check if the frequency is locked via remote control?

Answer

You can check the state of the external reference frequency with the STATus:QUEStionable:FREQuency register

STAT:QUES:FREQ:COND?

If the reference frequency is not locked, it will return a '2' or a '512'.

If everything is OK, it will return a '0'.