- What is the difference between Loadstar’s load sensors vs. conventional strain gauge load cells?
Conventional load cells
are built using strain gauges or piezo resistive devices which are
basically resistors. When a strain/stress is applied to the strain
gauge – it changes its resistance slightly. This change in
resistance is used to generate a mV signal that is amplified and
calibrated to measure loads. Typical full scale outputs are in the
20-40 mV range.
In comparison, our sensors are built using variable capacitors. When a
load is applied, the capacitance changes significantly and is converted
into a digital frequency signal. As the load changes, the frequency
changes. This frequency change can be measured very accurately and can
be converted into either a digital (USB, Bluetooth, Zigbee, WiFi) or
analog(0-5V, 0-20 mV, 4-20 mA) signal that is easy to input DIRECTLY
into a DAQ or a PLC or a PC.
- Do we need any signal conditioning electronics to operate the sensor?
No. If you use our iLoad
Digital USB sensors – you can plug directly into a PC without any
additional device. If you use our iLoad Analog sensors – you can
directly measure the 0-5V signal using a voltmeter and interpret
results, or use a DAQ or a PLC to digitize and interpret results. You
do not need additional equipment prior to digitization. Alternatively,
you can choose to use our DQ-1200 or DS-2100 series interface devices
that make it easy to digitize the signal and our LoadVUE software to
display the results on a PC.
- What is the input power requirement?
The iLoad Digital USB
load sensor takes 5V input directly from the USB port of PC. The iLoad
Analog load sensors require a regulated 5V supply:
Power Specifications:
- Maximum Input Voltage = 5V
- Input Voltage Noise < 100µVrms
- Input Current = 50mA max
- Is the power regulated inside the load sensor?
Yes, but only for the
iLoad Digital USB sensors – not the iLoad Analog sensors. You
would need to provide a 5V regulated power supply to the iLoad Analog
sensor. Any offset from this voltage will cause a similar offset in the
output voltage.
- How can I mount the iLoad Digital and iLoad Analog to my apparatus?
There are three mounting
pads in a pitch circle diameter of 2.760” and 120º apart at
the bottom of the iLoad sensors. Each pad has a #4-40 UNC X 0.25 deep
mounting hole which can be adapted to any flat surface. Detailed
outline drawings can be provided if requested.
We also have adapters as well as
version of the iLoad series with a #8-32 stud sticking
up from the center of the sensor that we can provide to
you as add-ons. Please contact us for information
regarding your particularf application needs.
- Can the iLoad series of sensors handle side loads?
At the present moment we
recommend that you take care NOT to apply side loads as it will affect
accuracy of the results. We are in the process of incorporating a
design change to improve resistance to side loads. We suggest that you
apply loads vertically to the center of the sensor through a ball
bearing as an interface between the sensor and the mating part.
- Are the sensors NTEP certified?
At the present time the
sensors are not NTEP certified. We are in the process of getting NTEP
certifications for some of our sensors and will make this available as
soon as we have it.
- What kind of forces can the sensors handle? (Impulse/Dynamic/Static loads)?
Generally speaking these
sensors are designed to be used in a static loading situation. The
sensors perform well in a dynamic environment as well but are limited
to approximately 3 to 5 millisecond response times. So if you are
looking for faster response rates you will need to purchase from some
one else. As far as impulse forces are concerned, because of the
response rate limitation, we will not be able to provide a true impulse
force if the time durations are less than 3 ms. YOU SHOULD ALSO TAKE
CARE TO NOT EXCEED THE OVERLOAD LIMITS DURING IMPULSE LOADING since
these loads can be several times the force exerted by a static load and
can cause a “set” and therefore a change in calibration if
care is not taken.
- Are the sensors temperature compensated?
The sensors are
temperature compensated in the operating temperature range if the rate
of change of temperature is gentle (less than 1 degree C per minute).
Sudden changes in temperature (“thermal shock”) can cause
temporary compensation errors.
Despite the compensation scheme, however, due to
accumulation of errors over a period of time, errors can add up to
several percentage of full scale if used without “tare”
over a few days. Long term stability is very difficult to achieve under
changing thermal conditions, so we recommend periodic
‘tare’ on the sensors to reset the zero value at the new
temperature condition.
- Can I get 3D solid models of our sensors for use in my design process?
Yes, we can provide 3D model of our sensors if requested.
- Which series of load cells is appropriate for use with a data acquisition system or a programmable logic controller?
You can use either the iLoad Analog series (0-5 V output) or the iLoad Mini series (frequency output).
- Do you supply a calibration curve with your sensors?
Yes. With our iLoad
Analog series sensors, we include a standard 9 point calibration over
the maximum allowable range (Full Scale) of loads that shows Loads vs.
Voltage output.
- What is the nature of the Force vs. Voltage Output?
The iLoad Analog series sensors have a linear output with 0.5V at zero load and 4.5V at full load.
- What is the pin-out of the iLoad Digital USB sensor connector?
The iLoad Digital USB has a Mini-B connector.
- Pin#1 = 5V power.
- Pin#2 = Data -
- Pin#3 = Data +
- Pin#4 = Not Used
- Pin#5 = Ground
- How many iLoad
Digital USB sensors can be connected to a PC?
In theory a typical PC can support up
to 255 serial devices (COM ports), but in practice this is limited by
the specific configuration of your PC's hardware.
Since the iLoad Digital USB sensor appears as a virtual COM
port on the PC, up to 255 such sensors could be connected to
a single PC as long as the PC is able to supply the needed
excitation voltage.
Each iLoad Digital USB sensor needs 50mA at 5V and a PC's USB port is
typically able to provide upto 100mA at 5V. So you can power
at least one iLoad Digital sensor per USB port. Since
some PCs have limited USB ports, you can use a powered USB
hub to expand the number of sensors you can plug to a PC.
- How can I build a scale with 4 iLoad Digital USB sensors?
You can connect at least 3 but typically 4 (for improved stability) iLoad Digital USB sensors to your PC either directly if it has 4 USB ports available or via a USB Hub that has 4 ports with a single UBS connection to the PC. Install and run LoadVUE Lite. LoadVUE Lite can display individual as well as the summed total of the weights or loads on the four sensors.
- Is it possible to interface iLoad Digital USB sensors to LabView or Matlab?
Our iLoad Digital USB sensor is plugged into a PC's USB port and shows up as a COM port (serial port) and responds to an ASCII command set. So any program that can communicate with a serial port can communicate with our sensor and retrieve the load values.
This can be tested by launching the Hyperterminal application from Windows XP, opening up the relevant COM port and sending the command "O0W1". The sensor will return the sensed load in millipounds as an ASCII string. LabVIEW or Matlab can retrieve this string and process the result.
See
Driver Installation and Hyperterminal Operation for more information and
examples using
LabVIEW and Matlab.
- Can I use a 9V battery to power the iLoad Analog sensor?
You can use a 9V battery
with a regulator to regulate down to 5V from 9V. You just have to be
careful that the battery doesn't deplete down to below 5 V since the
output signal will then start dropping with the drop in voltage.
- What is the wiring diagram for the output from the iLoad Analog sensor cable?
The iLoad Analog sensor has a USB MINI-B connector.
- Pin#1 = 5V power (Red wire)
- Pin#2 = Data -
- Pin#3 = Data + (Green wire)
- Pin#4 = Not Used
- Pin#5 = Ground (Black Wire)
- Is the output from the iLoad Analog sensor ratiometric?
No. However, an offset at the input power would cause similar offset in the output voltage.
- How can I build a wireless scale with your sensors?
You can connect at least 3 but typically 4 (for improved stability) iLoad Analog sensors to a DS-2100 Interface Device with WiFi connectivity. The DS-2100 device will appear as a virtual COM port on a PC equipped with a WiFi network card. LoadVUE or LoadVUE Lite can then communicate with the sensors and the DS-2100 and display individual as well as the summed total of the weights or loads on the four sensors.
- What is the difference between a CS Series and the iLoad Analog sensor?
The CS Series load sensors is superseded by the iLoad Analog series of load sensors. The iLoad Analog sensor has two important improvements:
Deterministic outputs
The CS Series load sensors had a 2V window of output voltages in the 0-5V range. However the output voltage at zero load could be anywhere in the 0.5 to 1.5V range and the output voltage at the full scale load could be anywhere between 2.5V to 4V. This made it difficult for an end user to write programs deterministically.
The iLoad Analog sensor is always close to 0.5V at zero load and always close to 4.5V at full scale loading. This lets a programmer to determistically set levels at which certain actions are taken.
Temperature Compensation
The CS Series load sensor was a purely analog sensor with temperature compensation performed in the analog domain.
The iLoad Series is built on a digital platform and has a microcontroller and a temperature sensor inside the sensor. The environmental compensation is done in the digital domain and is far superior to the results of the earlier design leading to better stability with temperature and time.
- I purchased a CS Series load sensors from you earlier. Do you still carry it?
For customers who purchased a CS Series sensor - we recommend an upgrade to the iLoad Analog series - or better still to the iLoad Digital USB series of load sensors. Please call us for help in moving to the new series.
- What is meant by “frequency” output? How can I interpret the frequency data to infer loads in lbs?
The iLoad Mini sensors
has 2 frequency outputs. When Control Input = logic ‘1’,
the Mini outputs the sensor frequency, Fsensor. When Control Input =
logic ‘0’, the Mini ouputs the reference frequency, Fref.
The compensated frequency Fcomp = Fsensor
- K*Fref, where K is a constant provided by
Loadstar. Loadstar would also provide the coefficients
for the quadratic equation to translate Fcomp
to weight.
- What are the differences between the DQ-1200 and the DS-2100 indicators?
DQ-1200 uses 12-bit A/D
for high speed data acquisition. DS-2100 uses 22-bit A/D for high
resolution data acquisition. Also the DQ-1200 offers high update rates
(as much as 200 samples per second) compared to the DS-2100 where it is
just a couple of times per second depending on the interface used.
Finally, the DS-2100 has a LED display to indicate loads whereas the
DQ-1200 does not have a LED display.
- Do I need to purchase LoadVUE or LoadVUE Lite to use iLoad Digital USB sensors?
You do not necessarily
need the software to use these sensors. If you have a terminal
emulator, such as Hyperterminal (included with standard Windows XP
Operating system under Start/All Programs/Accessories/Communications)
you can issue commands and obtain load in lbs directly. However, we
recommend using at least LoadVUE Lite for ease of use and to manage the
communications setup without understanding all the Windows jargon.
- What are the differences between LoadVUE and LoadVUE Lite?
| Feature |
LoadVUE |
LoadVUE Lite |
|
Compatible with iLoad Analog sensors |
Yes* |
Yes* |
|
Compatible with iLoad Digital USB sensors |
Yes |
Yes |
|
Maximum of 4 sensors |
Yes |
Yes |
|
Selective channel activation |
Yes |
Yes |
|
Selectable units |
Yes |
Yes |
|
Data Logging |
Yes |
No |
|
9-Point Calibration |
Yes |
No |
|
Selectable display refresh rate |
Yes |
No |
* Needs an interface device such as DQ-1200 or DS-2100.
- What is your warranty policy?
We have a 90 day warranty policy.
- What is your return policy?
30 days money back guarantee if returned in as new condition.
- What kind of payments do you accept?
We prefer payments by credit cards, checks or wire transfer.
- Do you give any educational discounts?
Yes. We offer a 10% discount on the total order price.
