ELAP CM78N, Operating Manual, Page: 2 / 7

Vv CM78N_C02_1.ING.doc 28/05/2009 page 2/6
OPERATING SPECIFICATIONS
POWER ON
At power on the display shows the current operational mode and
the identification of the sofware version.
DEFAULT CONFIGURATION
(See the tables at page 3)
If not differently specified in the order, the instrument is supplied
with the following configuration:
Basic setting:
F. 00000
Corresponding to:
Position visualiser, count x 4, NPN inputs
polarity, no decimal digits, input IN3
function=count block
Specific setting:
C. 00
Corresponding to:
LOAD by keyboard enabled, LOAD by
input on the closure state
POSITION VISUALISATION
It is assumed by convention that the default display unit is mm.
This is in no way obligatory. Keeping to the convention makes it
possible to use the mm/inch conversion facility.
PULSES COUNT
For all the selectable operational modes the instrument main
function is counting the pulses provided by the connected position
transducer.
The options relating to this function are, in detail:
bidirectional count x 4
bidirectional count - direct
monodirectional up-count
monodirectional down-count
Bidirectional Count
The bidirectional count is obtained by exploiting the phase
difference between the transducer channels to discriminate
between up- and down-count.
Direct Count/Count x4
One bidirectional count pulse includes
a complete pulse on both
count channels.
Incrementing the count by one for each complete
pulse gives as a result the
direct count.
That means that using the
direct count mode the count value obtained for each encoder turn
corresponds to the transducer ppr number.
Each
double-channel count has four fronts
: 2 ascent fronts and 2
descent fronts. Counting all the fronts gives as a result a
quadrupled count
number in respect to the encoder ppr number.
When calculating the multiplying factor it is necessary to pay
attention to the selected count mode.
Monodirectional Up- or Down-count
One single channel is used in this case, therefore the signals
cannot be used to discriminate the count direction.
The up or down direction count is chosen in the configuring
phase. The monodirectional count is always direct (x1).
MULTIPLYING FACTOR
The total value of the inputs counted according to the selected
mode is stored into the instrument count record. The count record
value is not displayed directly; the display value is the result of
the following calculation.
Display value = count record value x multiplying factor
This allows to display the counted pulses in the required
measuring unit.
The multiplying factor value can range between 0.01 and
9.99999.
MULTIPLYING FACTOR CALCULATION
To define the multiplying factor value it is necessary to know the
following data:
A
: value that must be displayed for each encoder rotation.
The value must be expressed in the resolution unit used
for the visualisation (see the example)
B
: number of the encoder pulses
C
: set count mode (x1, x4)
The value of the multiplying factor is the result of the following
calculation:
Factor
= A / (B x C)
To obtain that the visualised resolution is not beneath the real
resolution (B x C) must be
≥ A.
EXAMPLE
Suppose you avail on 50 mm diameter measuring wheel coupled
to a 500 ppr encoder. You wish to visualise the displacement with
0.1 mm resolution.
The value to be displayed for each encoder revolution
corresponds to the measuring wheel development expressed in
millimeter-tenths. Therefore the wheel diameter must be
expressed in mm-tenths for the calculation of the wheel
develoment.
Data
A
= 500 x 3.1415
B
= 500
C
= x4
Factor
= (500 x 3.1415)/(500 x 4) = 0.785375
ALARM THRESHOLDS
Both
operational mode 1
and
2
make available two alarms, which
are enabled by comparison in respect to the displayed count
record value. In the setting phase the alarms are indicated as
positive stroke end
and
negative stroke end
. The former is
enabled for value ≥ the count record, the latter for value ≤ than
the count record.
The alarms enabling is signalled by the relevant relay outputs
switching.
The operating mode of the two outputs can be selected: either
steady or by timed pulse. In case
timed pulse
outputs are
selected the required excitation time must be set in the relevant
parameter menu.
REMARK: For
operational mode 2
the alarms can be enabled
either in comparison with the absolute record or with the relative
record (see the specific settings).
ABSOLUTE/RELATIVE COUNT RECORD DISPLAY
CM78N-C02 avails on two separate count records: the absolute
count record and the relative count record.
The absolute record is shown in the main display page; a starting
value (LOAD value) can be loaded into the absolute record by the
relevant terminal box input. The absolute record is usually
referred to the machine zero reference and the LOAD value is
only entered at the machine initializing phase.
Pressing the key
P2
switches the visualisation to the relative
count record. In this phase a flashing dot appears on the display
second digit left.
The relative count record is an auxiliary visualization and can be
reset by pressing the key
R
. The relative count record is usually
referred to the working piece zero reference and is reset
whenever it is necessary.