Rosemount 3491, Справочное руководство, Страница: 94 / 152

Reference Manual
00809-0100-4841, Rev. AA
May 2007
Rosemount 3490 Series
4-62
About Totalising On
Model 3491
Totaliser (Cumulative totalised flow) on Model 3491
Model 3491 has one internal, 8-digit, totaliser, which is updated several times
per second. A Totaliser relay can be configured to output a pulse for each
increment to the Totaliser Count parameter. For information on setting up a
relay to output 'totaliser' pulses, see “Relays“ on page 4-39.
NOTE:
For totalising examples, see “Totalising examples“ on page 4-67.
NOTE:
Totalisers are set-up to operate with an input of PV in units/second. If the PV
value is a volumetric flow rate (e.g. m
3
/hour), the totaliser can accumulate this
volume of flow, therefore giving the total volume throughput.
Menu: MAIN MENU / SETUP / [CONTROL UNIT /] OUTPUT / TOTALISER
P530 Total factor (Factor default is 0.0)
One count is added to the Totaliser Count (D828) for a quantity of liquid as
defined by this parameter. The display units for D828 is defined by P531.
P531 Total units (Factory default is "None")
This parameter defines the units for the Totaliser Count (D828).
When using units of
gal
(US gallons), an 8-digit totaliser increments rapidly
and rolls over too frequently. To help with this, alternative totaliser units of
galx10
,
galx100
, and
galx1000
are available for selection. When these
special units are selected after selecting
gal
units, the totaliser factor (P530)
is automatically re-scaled by x10, x100, or x1000 depending on the selection.
NOTE:
If requiring Pumped Volume Totalising, see page 4-58.
P534 Pulse Width (Factory default is "100ms")
A Totaliser relay is energised for a programmed duration (P534) each time the
Totaliser Count (D828) is incriminated. Parameter P534 controls the 'On' time
and 'Off' time - i.e. the pulse width - and may be a value of between 10ms and
2.5s, changeable in steps of 10ms.
The rate at which the unit can output a totaliser pulse is entirely dependent on
the pulse width. Parameter P534 also determines the width of a pulse that is
output by a Sampler relay (see “Sampler Relay Output“ on page 4-66).
Menu:
MAIN MENU / MONITOR / [CONTROL UNIT /] READINGS / TOTALISER
D828 Totaliser
This parameter displays the Totaliser Count. To add this to the primary
display, see “Primary Display Options“ on page 4-71.
Resetting the totaliser On Model 3491
To re-set a totaliser to zero, display the Totaliser Count parameter e.g. D828,
and then press the button corresponding to "Reset" on display line 4.