Datasheet

52 Tachometer H7CX-R
■ Explanation of Functions
Basic Functions
(setting is performed with DIP switch)
Counting Speed
Set the maximum counting speed (30 Hz/10 kHz) for input. If con-
tacts are used for input signals, set the counting speed to 30 Hz. Pro-
cessing to eliminate chattering is performed for this setting.
Output Mode
Set the output method for control output based on the comparison
value. Upper and lower limit (HI-LO), area (AREA), upper limit (HI),
and lower limit (LO) can be set. (For details on the operation of the
output modes, refer to Output Mode Settings on page 55.)
Average Processing
Flickering display and output chattering can be prevented using aver-
age processing (simple averaging). Average processing can be set to
one of four levels: no average processing, 2 times (i.e., the average
of 2 measurement values), 4 times, or 8 times. The measurement
cycle will be equal to the sampling cycle (200 ms) multiplied by the
average processing setting (i.e., the number of times). Average pro-
cessing enables fluctuating input signals to be displayed stably. Set
the optimum number of times for the application.
NPN/PNP Input Mode
Select either NPN input (no-voltage input) or PNP input (voltage
input) as the input format. When using a two-wire sensor, select NPN
input. The same setting is used for all external inputs. For details on
input connections, refer to Input Connections on page 47.
Advanced Functions
(setting is performed with operation keys)
Decimal Point Position (dp)
Decide the decimal point position for the measurement value and
comparison value.
Prescale Value (pscl)
It is possible to display the rate of rotation or the speed of a device or
machine to which the H7CX-R is mounted by converting input pulses
to a desired unit. If this prescaling function is not used, the input fre-
quency (Hz) will be displayed.
The relationship between display and input is determined by the fol-
lowing equation. Set the prescale value according to the unit to be
displayed.
Displayed value = f
× a
f: Input pulse frequency (number of pulses in 1 second)
a: Prescale value
1. Displaying Rotation Rate
N: Number of pulses per revolution
Example:In order to display the rate of rotation for a machine that
outputs 5 pulses per revolution in the form @@.@ rpm:
1. Set the decimal point position to 1 decimal place.
2. Using the formula, set the prescale value to 1/N
× 60 =
60/5 = 12.
2. Displaying Speed
N: Number of pulses per revolution
d: Diameter of rotating body (m)
πd: Circumference (m)
Note: If the prescale value setting is incorrect, a counting error will oc-
cur. Check that the settings are correct before using this func-
tion.
Auto-zero Time (aut=)
It is possible to set the H7CX-R so that if there is no pulse for a cer-
tain time the display is force-set to 0. This time is called the auto-zero
time.
Note: Set the auto-zero time to a time slightly longer than the estimat-
ed interval between input pulses and within the setting range
(0.1 to 999.9 s). It will not be possible to make accurate mea-
surements if the auto-zero time is set to a time shorter than the
input pulse cycle. Setting a time that is too long may also result
in problems, such as a time-lag between rotation stopping and
the alarm turning ON.
Startup Time (stmr)
In order to prevent undesired output resulting from unstable input
immediately after the power supply is turned ON, it is possible to pro-
hibit measurement for a set time (0.0 to 99.9 s), the startup time. It
can also be used to stop measurement and disable output until the
rotating body reaches the normal rate of rotation, after the power
supply to the H7CX-R and rotating body are turned ON at the same
time.
Display unit Prescale value (a)
rpm 1/N
× 60
rps 1/N
Display unit Prescale value (a)
m/min
πd × 1/N × 60
m/s
πd × 1/N
d: Diameter of
rotating body
Startup time
Display
Power supply
Time
Output
(lower limit)
Comparison
value
(lower limit)