AMALGAMATED INSTRUMENT PM4-IVT, Operation And Instruction Manual, Page: 33 / 45

5.44 Total exponent scaling factor
Display:
E.SCL
Range:
0
to
9
Default Value:
0
Displays and sets the exponent factor for the display. The scaling factor can be set anywhere in the
range from 0 to 9. This factor allows a larger accumulated total by dividing the rate display value
down to a smaller number. For example a rate display in grams can be converted to kilograms by
setting
E.SCL
to
3
. The formula used to calculate the accumulated total display from the rate
display is as follows:
T otal = P revious total +
Rate display
×
dISP SCLE
tOtL SECS
×
10
ESCL
×
T s
Where: Ts is the time since the last sample in seconds.
Examples:
Example 1
- The instrument is connected to a flow meter and the rate is scaled to show litres per
minute (L/m). The total display is required in mega litres (ML). For a flow indication of 500 L/m
the total should increase by 500 litres or 0.0005ML in 1 minute. In the formula the rate display
will be 500, there is no display scaling factor (
dISPSCLE
) so enter this as
1
, the totaliser scaling
factor (
tOtI SECS
) will be 60 (seconds) since we are measuring in litres per minute and Ts will
be 60 (seconds) if we wish to see the total after 1 minute. Since we are measuring in mega litres
(Litres x 10
6
), the
E.SCL
value will be
6
.
T otal = P revious total +
500
×
1
60
×
10
6
×
60
T otal = P revious total + 0 . 0005( M L )
Example 2 - Rate of fill measured is to be in m
3
/hr (cubic metres per hour) with 2 decimal points
displayed. It is found that the total fill in one hour equals 4 times the rate indication, this will be
the
d.SCL
factor.
t.SCL
will be 3600 (seconds i.e. 1 hour in seconds),
E.SCL
will be 0 since
both rate and total are in cubic metres. For this example we will examine the increase in total
after 2 hours (7200 seconds). A rate of 35.8 m
3
/hr we would expect an increase in the total of
286.4 m
3
in 2 hours (35.8 x 4 x 2).
T otal = P revious total +
35 . 80
×
4
3600
×
10
0
×
7200
If
tOtI dCPt
is set to
0.02
then:
T otal = P revious total + 286 . 40( m
3
)
Adjustments required when different decimal points are used
If the rate decimal point setting
dCPt
and total decimal point
tOtI dCPt
settings are not the
same then adjustment will have to be made in the totaliser formula to compensate. The calculation
ignores the decimal points for the rate and total display so a value of 1.23 for example will be taken
as being 123 for calculation purposes. If the rate and total decimal point settings are identical
then this effect is canceled out. As an example if the rate display has 2 decimal points and the
total display has none then the formula must be adjusted to divide the result by 100 (e.g. 123/100
gets the figure back to 1.23). For Example 2 above the result of the formula would be correctly
displayed as 286.40 (assuming a previous total of 0) if the total display had two decimal points
PM4IVTMAN-2.3-0 33 of 45