Mitsubishi F700 Series Instruction Manual page 140

Pr.42
OFF ON
FU
ON
Example of output frequency detection signal (FU)
REMARKS
The output frequency compared with the set frequency changes depending on the control method.
Control Method
V/F control
Simple magnetic flux vector control
CAUTION
 Changing the terminal assignment using Pr. 190 to Pr. 196 (output terminal function selection) may affect the other functions.
Please set parameters after confirming the function of each terminal.
Parameters referred to 
Pr. 190 to Pr. 196 (output terminal function selection)
(3) Speed detection hysteresis (Pr. 870)
 This function prevents chattering of the speed detection
signals.
Pr.870
When an output frequency fluctuates, the up to frequency
signal (SU) and output frequency detection signals (FU,
FU2) may repeat ON/OFF (chatters). Setting hysteresis
to the detected frequency prevents chattering of these
OFF
ON
signals.
REMARKS
Setting a higher value to this parameter slows the response of
frequency detection signals (SU, FU and FU2).
Compared Output Frequency
Output frequency
Output frequency before slip compensation
Refer to page 123
Function assignment of external
terminal and control
4
129