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- What is the difference between Loadstar’s load cells 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 load cells 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 load cell?
No. If you use our iLoad
Digital USB load cells – you can plug directly into a PC without any
additional device. If you use our iLoad Analog load cells – 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 DS3000U or DS-3000UA 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 cell takes 5V input directly from the USB port of PC. The iLoad
Analog load load cells 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 cell?
Yes, but only for the
iLoad Digital USB load cells – not the iLoad Analog load cells. You
would need to provide a 5V regulated power supply to the iLoad Analog
load cell. Any offset from this voltage will cause a similar offset in the
output voltage.
- How can I mount the iLoad Digital load cells and iLoad Analog load cells 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 load cells. 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 load cell that we can provide to
you as add-ons. Please contact us for information
regarding your particularf application needs.
- Can the iLoad series of load cells 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 load cell through a ball
bearing as an interface between the load cell and the mating part.
- Are the load cells NTEP certified?
At the present time the
load cells are not NTEP certified. We are in the process of getting NTEP
certifications for some of our load cells and will make this available as
soon as we have it.
- What kind of forces can the load cells handle? (Impulse/Dynamic/Static loads)?
Generally speaking these
load cells are designed to be used in a static loading situation. The
load cells 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 load cells temperature compensated?
The load cells 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 load cells to reset the zero value at the new
temperature condition.
- Can I get 3D solid models of our load cells for use in my design process?
Yes, we can provide 3D model of our load cells 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 load cells?
Yes. With our iLoad
Analog series load cells, 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 load cells have a linear output with 0.5V at zero load and 4.5V at full load.
- Do your sensors support other platforms like the Macintosh?
Yes, we provide drivers for the following platforms:
- Mac OS X (Intel)
- Mac OS X
- Linux (kernel 2.6.9 or greater)
- Windows CE 6.0 (ARM/XScale Processor, x86 Processor)
- Windows CE 4.2 - 5.2 (ARM/XScale Processor, x86 Processor)
- Windows Mobile 6 (ARM/XScale Processor, x86 Processor)
- Windows Mobile 5 (ARM/XScale Processor, x86 Processor)
- PocketPC 2003 (ARM/XScale Processor, x86 Processor)
Note: Currently LoadVUE is not available for platforms other than Windows. However, our sensors can be read with any terminal or modem program that can read serial ports.
- What is the pin-out of the iLoad Digital USB load cell 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 load cells 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 load cell appears as a virtual COM
port on the PC, up to 255 such load cells could be connected to
a single PC as long as the PC is able to supply the needed
excitation voltage.
Each iLoad Digital USB load cell 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 load cell per USB port. Since
some PCs have limited USB ports, you can use a powered USB
hub to expand the number of load cell you can plug to a PC.
- How can I build a scale with 4 iLoad Digital USB load cells?
You can connect at least 3 but typically 4 (for improved stability) iLoad Digital USB load cells 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 load cells.
- Is it possible to interface iLoad Digital USB load cells to LabView or Matlab?
Our iLoad Digital USB load cell 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 load cell 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 load cell 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 load cell?
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 load cell cable?
The iLoad Analog load cell 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 load cell 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 load cells?
You can connect at least 3 but typically 4 (for improved stability) iLoad Analog load cells to a DS-3000 LED Display with digital usb uplink. The DS-3000 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 load cells and the DS-3000 and display individual as well as the summed total of the weights or loads on the four load cells.
- What is the difference between a CS Series and the iLoad Analog load cell?
The CS Series load cells is superseded by the iLoad Analog series of load cells. The iLoad Analog load cell has two important improvements:
Deterministic outputs
The CS Series load load cell 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 load cell 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 load cell was a purely analog load cell 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 load cell. 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 cell from you earlier. Do you still carry it?
For customers who purchased a CS Series load cell - we recommend an upgrade to the iLoad Analog series - or better still to the iLoad Digital USB series of load cells. 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 load cells
has 2 frequency outputs. When Control Input = logic ‘1’,
the Mini outputs the load cell 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 DS-3000A and the DS-3000U LED Displays?
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 load cells?
You do not necessarily
need the software to use these load cells. 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 load cells |
Yes* |
Yes* |
|
Compatible with iLoad Digital USB load cells |
Yes |
Yes |
|
Maximum of 4 load cells |
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-3000.
- 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.
