The tester cannot start to run a test under the 
following conditions: 
  A protection setting has been tripped; when a 
protection setting has been tripped the 
corresponding error message is displayed on 
the screen. See page 261 for a comprehensive 
list of the all the setting errors. 
  The INTERLOCK function is ON and the 
Interlock key is not inserted in the signal I/O 
port (page 144). 
  The STOP signal has been received remotely. 
  If Double Action is ON, ensure the START 
button is pressed immediately after the STOP 
button (<0.5s).  
When a test is running the voltage output 
cannot be changed, unless the test is under the 
special manual mode. See page 102 for details.