7088-8000
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Setting the Current Loop Span
After the current loop has been calibrated, the span (flow rate associated with the 4 to 20
mA output) can be set.
To set the span:
1. From the
4-20 mA
options group, click on the
4-20 mA
check box to enable the current
loop function.
2. Click on the
FLOW RATE FOR 4 mA
text box.
3. Enter the flow rate that equals the 4 mA (minimum) reading.
4. Click on the
FLOW RATE FOR 20 mA
text box.
5. Enter the flow rate that equals the 20 mA (full scale) reading.
F.4.9 RELAYS OPTION GROUP
The
RELAY
option group is accessed by clicking on
RELAY(S)
in the Options Column.
This group contains the options for configuring and testing the relays.
NOTE:
Refer to Section 2.5 for information on replacing the relay and to Section 2.4.4 for
information on connecting the relay wiring.
IMPORTANT:
The relay and current loop functions on the DCT1088 are mutually
exclusive. Only one of these functions can be enabled at a time. When
programming, testing, or operating the relay on a DCT1088, the current
loop function must be disabled. (The
4-20 mA
check box must be
unchecked.).
Programming the Relays
One optional programmable relay is available for the DCT1088 and four optional relays
are available for the DCT6088 for functions such as alarm, pump control, etc. The relay
ON and OFF conditions can be independently programmed for each relay for a specified
flow, signal strength, or totalizer value. Alternatively, the relay can send a pulse to a
remote device (for example, a totalizer, sampler, or chlorinator) whenever the internal
totalizer advances by one unit. The relays can be tested (manually turned on and off) by
clicking buttons on the screen.
The output for the
PULSE
selections is limited to one cycle per second. The pulse duration
(relay ON time) is approximately 200 milliseconds. If the totalizer increments at more than
once per second, the flowmeter keeps track of how far behind the relay pulses are. The
flowmeter then catches up when a flow condition occurs where the totalizer increments at a
rate of less than once per second. To prevent the relay pulse output from falling behind, the
totalizer multiplier (Section F.4.7) should be selected such that at the maximum anticipated
flow rate the totalizer increments at once per second or less. For example if the totalizer
unit is in gallons and the maximum anticipated flow is 600 gallons per minute (10 gallons
per second), a multiplier of 10 should be selected.
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