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using an accurate 100 Ohm resistor, the overall loop resistance is 200 ohms due to an additional 100 Ohms
series protection resistor. This means that a sensor at a full 20 ma current output, approximately 4 volts
should be allotted for overhead voltage. This is typically not an issue when an external voltage source is
provided to operate the sensor that may be in the 18 to 24-volt range. However, if a 12.5-volt battery is
used to source the voltage for the sensor in the current loop, then only 8.5 volts will be supplied to the
sensor at max sensor current output. Therefore if a full 12 volts is necessary for the sensor, an external
loop supply will be necessary or alternately the sensor may be wired to a single-ended voltage input with
the use of an external 100 Ohm accurate and stable resistor also attached to the voltage input port.
Warmup
Analog sensors are powered by the station via one of several outputs:
VREF (reference voltage) which provides 2.5V, terminals #25 and #21.
Switched Power which provides whatever voltage is powering the station, presumably 12V, on
terminal #8.
Normally, these outputs are off. Prior to making an analog measurement, the system will turn on these
outputs. After that, the system waits
Warmup
amount of time (which is expressed in seconds) before
measuring the output of the sensors. This
Warmup
time gives the sensors a chance to power up and
prepare their outputs.
If
Warmup
is set to zero, the system will not wait at all prior to measuring. The value
Warmup
should be
set to depends on the analog sensor being measured.
Warmup is also used for
Digital and SDI-12
type sensors. If a such a sensor (or a wind
sensor that uses digital or SDI-12 inputs) is set up with a warmup, then VREF and
Switched Power (SWD#1) will both be turned on. If warmup is set to zero, those
output lines will not be turned on. This is different for
Analog
measurements which
turn on the lines regardless whether warmup is zero.
10.3.5
Measure Type: Battery
This type measures the voltage of the battery connection to the station. This measurement is a useful
diagnostic for tracking the performance of the battery and any solar panel or other charging equipment.
10.3.6
Measure Type: Wind
The Wind measure type makes it possible to do vector averages of data from wind speed and direction
sensors. The normal average function does not typically work for wind sensors because of the circular
nature of the direction measurement. The vector averages take into account the 0 to 360 degree
crossover to produce accurate average.
Follow these steps to setup for Wind averages:
Step 1) Setup a measurement to measure the wind speed (see section
Set measurement interval for how often you want the speed measured
Use slope/offset/equation to properly scale the speed to the desired units.
Summary of Contents for SUTRON XLINK 100
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