4230 Flow Meter
Section 2 Programming
2-17
The following will appear if you are measuring D. O:
(or mg./L. depending on units selected in Program.)
A set of menus similar to those shown above for pH, D.O., and
temperature will then appear for the YSI 600 Sonde, if you have
selected it. You can set hysteresis for YSI-pH, YSI-D.O., YSI-Con-
ductivity, and YSI-temperature, if these parameters have been
turned on in previous program selections.
2.7.1 Optional Outputs After all the HYSTERESIS menus have been set, press Enter.
The display will return to the Setup menu. This time select
OPTIONAL OUTPUTS.
ALARM BOX refers to an external accessory used to signal
alarms from flow meter measurements. See Section 4 for more
information. The choice of SERIAL OUTPUT will eliminate
ALARM BOX as an option. Likewise, the choice of ALARM BOX
will eliminate SERIAL OUTPUT as an option.
If you select any of these OPTIONAL OUTPUTS, the flow meter
will request that you turn them on or off. If you are running on
battery, select OFF for all unused outputs.
ANALOG OUTPUT refers to the flow meter’s capability of man-
aging associated equipment through a 4-20 mA current loop. The
4-20 mA current loop is a common method used to control indus-
trial processes that are variable (rather than just fully off or on).
At the lower value (4 mA) the control is turned off (0%); at 20 mA
the control is completely turned on (100%). In between, rates
range from 1 to 99%. A typical application is a chlorinator, which
must vary in application of the chlorine gas as the amount of
water passing through the system increases or decreases.
Current ranges other than 4-20 mA are also in use, although
they are less common than 4-20 mA. Examples are 0-20 mA (sup-
ported by the flow meter on the internal card only) and for longer
current loops, 10-50 mA (not supported by the flow meter).
Isco offers two different arrangements for the 4-20 mA control
circuit. You can have either or both with the same flow meter.
One arrangement requires the use of an external accessory, the
4-20 mA Output Interface (see Section 4). This module connects
to the flow meter and a source of AC power and contains the cir-
cuitry necessary to create the 4-20 mA current loop. This
accessory connects to the flow meter through the Interrogator
connector.
The other 4-20 mA option is a board installed inside the flow
meter that contains circuitry for up to three separate, isolated
4-20 mA current loops. This option can also be ordered with one
or two current loops supplied. If you use both the external con-
verter and the internal board, you can have a total of four
current loops controlled by the same flow meter. The internal
DO ENABLE/ALARM
HYSTERESIS X.XXX PPM
OPTIONAL OUTPUTS
• ANALOG OUTPUT • • SERIAL OUTPUT • • ALARM BOX •
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