Omron K3MA-J User Manual page 90

CHAPTER 6 FUNCTION DESCRIPTION
Unit conversion
(r/s): (r/min)÷60
Unit conversion
(m/s): (m/min)÷60
(mm/s): (m/min)×1000÷60
Auto-zero
6-8
Conversion of the input pulse frequency to the rotational speed involves the following
scaling formula.
Where;
P: Number of pulses per rotation
inp: Input pulse frequency (Hz)
dsp: Rotational speed (r/min)
Conversion of the input pulse frequency to the circumferential speed involves the
following scaling formula.
Where;
π:
Circular constant
P: Number of pulses per rotation
R: Diameter of rotor (m)
inp: Input pulse frequency (Hz)
dsp: Circumferential speed (m/min)
K3MA-F has an input pulse frequency range of 0.05 to 30 Hz or 0.05 to 5 kHz, and
hence the maximum interval between pulses is 20 seconds.
This means that the product may provide a lower-limit signal action as late as a
maximum of 20 seconds after receiving the last pulse, which results in a poor
responsibility for the lower-limit action.
To eliminate such a situation, K3MA-F has an auto-zero function that shifts the
input pulse frequency to zero forcedly when no pulse is received for a predetermined
time.
This function improves the product responsibility for the lower-limit action.
The time between reception of the last impulse and zero-shifting of the input pulse
frequency is called the auto-zero time. The auto-zero time can be specified using the
"auto-zero time" parameter. Specify the auto-zero time somewhat longer than the
expected longest interval between input pulses.