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October 2007
Analog Outputs
Alarm Outputs
2-8
Note: When the OptiSonde is being programmed, the analog outputs
provide 4–20 mA signals representing the designated
parameters.
For 4–20mA output, connect to terminals labelled 4–20 (+) and
•
RTN (–).
Note: The maximum load allowed for current output is 500 Ohms.
Example: Assume a temperature output, scaled to range from 0°C
(T
) to 100°C (T
lower
upper
23°C (T
): The current output is calculated by:
actual
(
T
------------------------------------------ -
Iout
=
(
T
yielding an output current of 7.68 mA.
(
23 0
–
----------------------
(
100 0
–
The alarm output connects to the contacts of a 7-Amp, Form C
(SPDT) relay.
Make connections as follows:
•
For normally open contacts, connect to NO and COMM.
•
For normally closed contacts, connect to NC and COMM.
Any available parameter can be used to control an alarm relay by
programming the parameter name and its threshold values. An alarm
can also be programmed to monitor the state of the Control, PACER
Balance, or Service indicators. (See Chapter 4 for programming
instructions.)
Two threshold values are programmed for each parameter—an upper
and a lower value. These values designate an alarm band. How they
are used depends on the alarm type programmed. Details of the alarm
bands are shown on the following pages.
), with a measured actual temperature of
)
–
T
actual
lower
×
(
)
20 4
–
+
)
–
T
upper
lower
)
×
(
)
16
+
4
=
7.68mA
)
(2-1)
4
(2-2)
Installation
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