
7. PARAMETER SETTING
VM-5S
-54-
7-11 DETERMINATION OF HYSTERESIS
The hysteresis can be set by means of the jumper pins on the circuit board to 0.1V, 0.2V 0.5V or
1.0V. It is preset to 1.0V at the factory, but may have to be changed if any of the following
conditions apply.
• The input signal level from the sensor (minimum level over the full speed range) is
lower than 3Vpk-pk.
• The noise of the input signal from the sensor (maximum level over the full speed
range) is higher than 0.5Vpk-pk.
Setting
Conditions
• If you have to set the hysteresis, make sure that the following conditions are met.
Otherwise correct measurement is not possible.
C
ondition (1) a-(hysteresis set value)>2V
C
ondition (2) (hysteresis set value)>b
If these conditions cannot be met, the following measures must be taken.
To meet Condition (1) :
• Select a narrow set gap and a high input signal amplitude.
• Select a larger shaped speed detection target and a high input signal amplitude.
To meet Condition (2) :
• Take measures against noise to reduce the noise level.
• The higher the values in conditions (1) and (2), the higher the measuring stability.
We recommend that you make the values as high as possible.
a: Min. Value of
Input Signal
b: Max. Noise
Value
Input Waveform
Mandatory