5.3 Description of Function Codes 5.3.2 E codes (Extension terminal functions) 
 
 
Reference loss detection (continuous running frequency)
 
 
When  the  analog  frequency  command  (setting  with  terminal  [12],  [C1]  (C1  function),  terminal  [V2],  or  [C1]  (V3 
function) has dropped below 10% of the reference frequency within 400 ms, the inverter presumes that the analog 
frequency command wire has been broken and continues its operation at the frequency determined by the ratio 
specified by E65 to the reference frequency. And “REF OFF” signal comes on. 
( Function codes E20 to E24, E27, data = 33) 
When the frequency command level (in voltage or current) returns to a level higher than that specified by E65, the 
inverter presumes that the broken wire has been fixed and continues to run following the frequency command. 
 
 
Fig. 5.3-25 
 
In the diagram above, f1 is the level of the analog frequency command sampled at any given time. The sampling is 
repeated at regular intervals to continually monitor the wiring connection of the analog frequency command. 
•  Data setting range:0 (Decelerate to stop), 20 to 120 (%), 999 (Disable) 
 
Avoid an abrupt voltage or current change for the analog frequency command. An abrupt change may be 
interpreted as a wire break. 
Setting E65 data at “999” (Disable) allows the REF OFF signal (“Reference loss detected”) to be issued, 
but  does  not  allow  the  reference  frequency  to  change.  (The  inverter  runs  at  the  analog  frequency 
command as specified.) 
When E65 = “0” or “999,” the reference frequency level at which the broken wire is recognized as fixed is 
“f1  0.2.” 
When E65 = “100” (%) or higher, the reference frequency level at which the wire is recognized as fixed is 
“f1  1.” 
The reference loss detection is not affected by the setting of analog input adjustment (filter time constants: 
C33, C38, C43, C76). 
 
 
Terminal [C1] (V3 function) (extension function selection) (Refer to E61)
 
 
A detailed explanation can be found in the function code E61. 
 
   
Reference loss 
detection REF OFF 
Frequency command 
(internal data)