Teledyne 4220, Инструкция по установке и эксплуатации, Страница: 44 / 198

4220 Flow Meter
Section 2 Programming
2-16
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
current loops are brought out to a 6-pin M/S connector in the slot
where the
Modem connector is usually mounted.
To activate the internal analog output(s), return to the main
screen and press
4 , 2 , 0 .
Additional information for the internal analog output board,
including specifications for the loops, is found in Section 5.3.2.
CAUTION
Each 4-20 mA output represents a constant draw on the flow
meter of at least 16 mA, whether activated or not. While 4-20
mA applications are generally made in installations with com-
mercial power available, Teledyne Isco suggests the following
for those who have a 4-20 mA output in a battery-powered
installation.
Use with battery powered flow meters only if:
•The battery is continuously on charge (for example with a
Solar Panel Battery Charger).
•The battery is very large, such as a deep-cycle or marine type
battery, or an Isco 35 Ampere-hour lead-acid battery.
•Use only one 4-20 mA output.
•Keep in mind that programming choices also affect power
consumption. Use “minimum” settings on the flow meter wher-
ever possible. (See Section 1, Table 1-5.)
Even with these circumstances, you may expect significantly
shorter charge life from your battery. To determine the effect of
this extra current draw on battery life, please refer to the sec-
tion
How to Make Battery Calculations , at the end of Section
1.
The following menus determine the behavior of the 4-20 mA
current outputs. If you select ANALOG OUTPUT (another term
for the 4-20 mA Output) and the flow meter is equipped with the
optional internal board or the 4-20 mA external accessory has
b e e n t u r n e d o n , R A N G E , S M O O T H I N G, a n d M A N UA L
CONTROL will appear:
CAUTION
If you do not have the proper hardware installed and you press
4 - 2 - 0, and the number of analog outputs is not
zero , the
external 4-20 mA conver ter will not work properly. If this
ANALOG CAPABLE (‘0’ TO DISABLE)
OUTPUTS 3
❚
(‘EXIT PROGRAM’ WHEN DONE
ANALOG OUTPUT
• EXTERNAL 4-20 MA • • (RANGE) • • (SMOOTHING) • •