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WHAT'S
NEW ABOUT RADARTRON 2250D?
Scale-Tron's well known RadarTron
microwave moisture sensor has been
upgraded in several important ways, as follows:
Digital bidirectional
communication through both RS232 and RS485 connections, to transmit
moisture readings and allow menu-style setup and calibration. RS
232 allows easy connection to most computers and PLCs while RS485 can
communicate reliably up to 4000 ft, eliminating the need for extra
repeaters. Any number of sensors can share the same RS485 line in
daisy-chain fashion, to a single computer or PLC port. An optional module converts this back to either RS232
or USB for connection to the computer. The digital interface is
fully compatible with Command Alkon and other batch controllers.
Totally new circuit
board with digital processing, allowing the filtering and averaging
parameters to be adjusted when necessary for special applications.
Shorter body,
sealed construction and smaller mounting flange, allow installation in
crowded spaces while still providing the 'reach' that is sometimes
needed to get into the flow region
Analog output;
both 0-20 and 4-20 mA are selectable. If 0 - 10 volt output is
desired, a resistor can be connected at the receiving end to convert the
current signal into a voltage signal, giving higher accuracy than with a
standard voltage signal.
Temperature sensor
situated near the faceplate gathers an accurate average temperature of
the material surrounding the faceplate. This is used to compensate
for the small change in water's dielectric constant with temperature,
improving accuracy over the temperature range, as well as being
available through the digital output for use by the computer.
Low material level
output; the previous 1400C model sensed when the faceplate was
uncovered and froze the moisture reading, preventing an abnormally low
reading from spoiling the batch in process. 2250D has this same
feature but also allows this output to be used for external alarms.
The junction box is available with a relay for this purpose.
Multiple material
calibration; up to16 separate material
calibrations are available, for use in different materials. This
feature allows 2250D to be used in those awkward applications where
different materials are used from time to time in a single bin.
24 volt power;
2250D will run from the batching controller or any inexpensive
unregulated power supply between 11 and 30 volts DC.
CALIBRATION SYSTEM
Calibration is a tedious
chore that has to be accomplished. The 2250D sensor is precalibrated with
'average sand' in our test lab. Because materials differ, however,
even in building sand, each sensor should be checked after installation
and trimmed if not up to par.
In place of the 1400C's
awkward internal calibration pots, 2250D is sealed and calibration is
done through the digital interface. If you are using the digital
interface as your main connection to a PC computer controller, all you
need for calibration (and local moisture display) is the Windows
software utility provided with the sensor or, if lost, the Hyperterminal software that comes with
Windows. This is found through the Start menu under Accessories,
Communications. If you are using the RS485 or analog connection,
or are connecting to a non-PC system, such as a PLC, use the Programming
Cable to connect to a Windows computer, laptop or PDA.
Once on-line, the setup
and calibration menu guides you through the steps. You need
several readings along with the true moisture values obtained from
oven-dry or bakeout tests, over a wider range of moisture than will be
used in practice. Once these values are entered, calibration is a
click away.
For multiple materials,
this process is repeated for each material. Yes, it's tedious, but
anyone who tells you that they have a simpler system is just not telling
the truth. There is no substitute for proper calibration; no
system will perform accurately without it.
NEW
MIXTRON SENSOR
Now that we have
RadarTron 2250D under our belts, we can concentrate on its sister -
Mixtron D. We are presently finalizing this new sensor, which has
most of the advantages above plus a few of its own. Compared with
our present Mixtron sensor, the digital Mixtron has signal
averaging built in, with programmable parameters for unequalled accuracy
in most mixers. General appearance, cables and connections are
similar to RadarTron 2250D.
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