7088-8000
-167
The net totalizer can either increment or decrement depending upon the direction of the
flow. Since the external totalizer (driven by the net totalizer pulse) can only increment, the
flowmeter stops transmitting pulses whenever negative flow is being measured. The
flowmeter keeps track of the negative flow and does not start sending pulses to the external
totalizer until the measured negative flow has been canceled out by positive flow. If an
application has negative flow for extended periods of time, separate external totalizers
should be used, driven by the positive and negative totalizers. The net flow total can then
be determined by subtracting the value for the negative external totalizer from the value for
the positive external totalizer.
To program the relays, follow these steps for each individual relay:
1. From the
RELAY
options group, click on the down arrow to the right of the
RELAY
NUMBER
text box.
Relay numbers
1
through
4
are available.
2. Click on the desired relay number.
NOTE:
When configuring the relay for the DCT1088, relay number
1
must be
selected.
3. Click on the down arrow to the right of the
MODE
text box.
The following relay mode selections are displayed:
!
OFF
- (for turning off the relay function)
!
PROGRAM
- (for setting the relay ON and OFF conditions)
!
PULSE NET
- (for sending a pulse to a remote device whenever the net totalizer
advances by one unit)
!
PULSE POS
- (for sending a pulse to a remote device whenever the positive
totalizer advances by one unit)
!
PULSE NEG
- (for sending a pulse to a remote device whenever the negative
totalizer advances by one unit)
If the
OFF
selection or one of the
PULSE
selections is chosen, the relay configuration
procedure is completed. If
PROGRAM
is selected, the relay ON and OFF conditions
must be set in the following steps. The OFF condition value should be entered in
conjunction with the ON condition value to establish a “dead band”. This prevents the
relay from continuously cycling on and off when the flow is close to the ON or OFF
value. For example, if the ON condition is
FLOW > 250
gallons per minute, the OFF
condition may be set at
FLOW < 240
gallons per minute. At these settings, the relay
turns on when the flow exceeds 250 gallons per minute and does not turn off until the
flow falls below 240 gallons per minute.
4. Click on the down arrow of the first ON condition pull-down list.
The following ON condition selections are displayed:
!
FLOW
!
SIG STRENGTH
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