Ultrasonic level measure
The result is best viewed with the Level program but is not really needed because any simple text based terminal program can communicate with the level probe and show the level information.
The complet set gives you the possibility to study the physic of
ultra sound technics. All probe parameters are adjustable and programmable
with a simple mouse click and any change is real time displayed on screen.
The ultrasonic burst power, length, frequency, interval and more can be
modified and the result is immediatly visible. The 6350mm (250inch) working
range meets most
applications. Fit the probe on a pipe, load the program and start.
See also our new programmable Accucontrol for fuel or water tanks level measure.
With Low tank alarm, slowly decreasing level (=tank leak alarm) and level increasing alarm to not forget stopping when filling...
This program receives the Level Probe data's via the RS232 communication port and shows all the probe parameters, and it also sends the commands to the programmable Level Probe. A graphical drawing of the actual representation of the waves received by the ultrasonic transducer is shown on the screen. The patterns can be frozen with their own parameter setting. One can then proceed on another line, change any of the parameters and examine the difference.
The program can record sequences of ultrasonic propagation shape and
play them back by command button [#]. From this moment all data's coming
from the probe will be recorded into a file. A sample file "Level.spl"
is also provided and can be played right after installation of the Level
The Level program is free to download.
Just click here to get the complete Level program Setup (1 file).
The Level program gives all the information concerning
the programmation of the probe with details on all the commands. For experimenting,
the programmation of the parameters is easly made with the Level program
where only mouse clicks are required but any (hyper) terminal program where
characters can be typed in and sent can be used. View therefore the list
of all commands that can be sent to the probe. A parameter can be changed
by sending the corresponding command to the probe. The commands are characters
code, sent/received via the built-in RS232 interface.
Command list. More details in the Level program.
Sending 1, 2 or 3 to the probe force data's send mode to; 1, send info non stop. 2, just before each new burst. 3, only on request. This with the actual probe baud rate setting. The diagram display and the parameter refresh stop in mode 3. Request for a parameter value is done with its appropriate command sent to the probe. [o] returns the actual transmit mode.
? Returns the actual measured distance. ( ex: D2145 ) for 2145mm. Check command receive mode, especially mode 3 where info's are only send on request with there apropriate command.
A Activates the Level Auto tune function. From there the parameters are adjusted in the probe in order to track the distance info over the full range. If this parameter is saved into the probe, the Auto tune mode [A] is selected at power up.", 1, " [A] Auto tune. [a] returns tune mode.
B b Increases (*2) decreases (/2) the probe baud rate. This new value will only take effect if saved into the probe [W] and after restart [Z] or powerup. Choose maximum baud rate to speed up the graphic diagram refresh if used. Choose minimum baud rate for long distance communication between probe and PC or terminal where no graphic need to be displayed. [x] returns the probe baud rate.
c Will return the probe temperature in 1/10 degrees celcius. The temperature is mesured under the circuit and next to the ultrasonic transducer. This position give as result a close temperature value of the top air cullom in the pipe, but the bottom temperature of the bottom remains unknown.
D d Increases/decreases the dead time distance with 1cm. Any signal received in this time, short time just after the burst, will not be marked as a valid distance echo. This distance should not be too short to prevent the burst noise to be taken as a valid echo signal. Sending [m] to the probe return the Dead Time.
e Returns the Echo bounce. The echo bounce is the amount of pulses received by the transducer starting from the first one marking a valid echo (after the Deadtime) until no more signal is received for this last burst. Increasing the burst length [R] and/or burst voltage [U], will make the sound wave produce more than one echo as visible on the line diagram and Eb. if too strong, the burst will make more dan one traject. Down to the liquid level, up and down and up again.
F f In/decreases the ultrasonic transducer frequency. This 25Kc, very high quality transducer, still gives good result on other frequencies. The frequency is set by default to 25 Kilo-Cycles/s. But can be < > tuned. The new working Fq can be saved as the rest. If wanted, one can replace the 25Kc transducer by a small band 40kc (maximum tested) type without further change.
g Returns the Burst bounce (help if you know a better name!). The Burst bounce is the value of all received pulses just after the burst and before Dead time is elapsed. These are the oscillations of the transducer after the burst, the echo of the physic irregularyties of the mechanic probe connection to the pipe, quasy immediate standing waves created by the presure of the ultrasonic burst and the reflection of the air gap, the channel that lets escape the air of the pipe. Notice value change of the Burst bounce while manually adjusting parameters.
Sending h to the probe makes it send back a small text file containing ALL available commands. This command is non relevant with the Level program where all this happens automatically, but helpfull when the ultrasonic probe is used with a terminal or any simple communication program, where command characters are send manually one after each other.
I i In/decreases the interval between each ultrasonic burst. Choose a large interval if there is no need to have a high burst rate when only a distance level control (display or screen) is used and the liquid level is not supposed to change quickly. This may save power. As to the life time of the transducer, it should not make any difference. The transducer is low voltage driven and passed long tests over 100V.
M Disables the Auto tune mode and sets the probe to manual control. Use Manual control to ajust any parameter. After power up or reset, if Manual mode was saved, the probe starts to work with the saved parameters and will not adjust or change any. Manual mode enables to adjust the working of the probe on a selected range and pipe shape. [a] returns tune mode.
n Returns the (8bit) Pulse Wide Modulation value of the transducer output voltage driver. This is a control value using to tell if the driver is operating. On this low duty voltage, the driver is not likely to be damaged. This feature is more useful for high tension probe.
R r In/decreases the periode amount sent with each ultrasonic pulse burst. The default setting is 4 periodes. Watch the burst noise (Bd) while increasing this parameter and make sure that the Dead Time is long enough. [P] returns the periode amount value.
S Resets all the parameters to default setting. The default setting can not be overwritten, but may be saved to the probe. Send default command [S] and read all default values with the Level program or after sending [S] + [p] with a communication terminal.
W Writes (saves) all the (changed) parameters into the probe microcontroller non volatile flash EEPROM. By next power up or reset, the last saved parameters will be used for further processing.
T t In/decreases the temperature propagation coeficient of ultrasonic sound waves in air. This parameter is used by the micro-computer probe, to calculate a more accurate time/distance echo. The default value is 0.60m/s/C. This is approximately the general admitted increasing of ultrasound propagation speed in air per degree Celcius. Known as a Constant, there should be no need to change this value. But as all the other parameter it is possible. [k] Returns the coeficient.
U u In/decreases the burst voltage on the ultrasonic transducer. 24dc probe supply will give a maximum of app. 20V on the transducer. For 12Vdc, half of it. A few volt is enough with this high quality transducer for 3 meter in a clean PVC pipe. [s] return the burst voltage.
v V Decrease/increases the ultrasonic propagation speed value. The default value is 331,0 m/s. But because other factors can influence the propagation speed of sound waves in air, the parameter can be adjusted to best knowledge. The parameter changes are made in steps of 0,1 m/s. [w] Returns the us speed.
Z Resets the probe microcontroller. The probe will start again
with the last saved parameters (W).
Installation schematic; The probe blue top (with the inside!) is what
you get. Ultrasonic sensor probe 12/24Vdc. PVC case. Fit on an 50mm
pipe (PVC or any pipe, length up to 6,5m, 250inch). Suitable for water
level or any non corrosive liquid medium. Not for any explosive liquid,
vapour or damp.
The probe cable wire, is terminated with a RS232 plug that can directly be plugged into the PC.
The probe supply power,10 to 35Vdc 25mA, can be connected to the red (positive) and black (negative) wires coming out of the connector. 12Vdc is enough to measure lengths up to 4m (>150inch). For more, 24Vdc is recommanded.
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