Table of Contents
Advertisement
Configuration
February 2023
Note
Choose Pulse wheel if safety function Direction of rotation or Speed + Direction has
been chosen.
Trigger wheel, number of teeth
Enter here the number of teeth of the used trigger wheel. This number together with the
signal frequency is used for the calculation of the speed. If only one trigger mark (groove
or tooth) is available, enter "1". The maximum number of teeth is 1000.
Symmetry
Enter here the pulse width ratio of the input signal. This parameter is used together with
the maximum speed (parameter Maximum speed) to adjust the noise pulse filter. The
filter has the widest passband at a symmetry setting of 1%.
Use the TTL signal to define the pulse width ratio. Measure the TTL signal at arbitrary
speeds with an oscilloscope at the socket Pulse (see
to check the pulse width ratio at nominal speed and to adjust it if necessary as the pulse
width at nominal speed is crucial for the noise pulse filter.
Note
If Pulse wheel has been chosen for parameter Type of measurement (Pulse shape), set
the parameter Symmetry to 50%. The actual signal symmetry has to be checked at front
socket Pulse (see
The maximum permissible tolerance at nominal machine speed is -20% of the entered
symmetry value. Wider respectively longer pulses cause higher symmetry values than the
entered symmetry value. These pulses are not filtered. Smaller respectively shorter pulses
cause symmetry values lower than the entered value. All pulses with a symmetry value
below the entered value minus 20% are identified as noise pulses.
Example: With an entered symmetry of 20% the actual symmetry may not be below 16%,
measured at the front socket Pulse, at nominal speed. All pulses with a symmetry above
the limit of 16% are used for speed calculation, respectively detection of rotational
direction. Pulses below this limit of 16 % are identified as noise pulses and filtered out.
Above this limit the symmetry of the input signal may vary.
Figure 5-30
portion, which is smaller than 50% must be used to define the symmetry as the entry
range of the parameter is limited to 1 to 50%. This could be either pulse width or pulse
pause. Calculate the symmetry with the following formula.
Symmetry = Period portion
Example with Period portion
(period duration) = 20 ms:
Symmetry = 4 ms*100% / 20 ms = 20%
104
Socket
Pulse) and may vary within a range of 40% to 50%.
and
Figure 5-31
show symmetry examples based on the TTL signal. The period
*100% / (Pulse width + Pulse pause)
≤50%
(pulse width) = 4 ms and Pulse width + Pulse pause
≤50%
Operating Manual
Socket
Pulse). Emerson recommends
MHM-97442, Rev. 2.06
MHM-97442
Advertisement
Table of Contents
