Reduce noise by placing i4xx cards near sensors and up to 100 meters from noisy computer.
Why Is instruNet Better Than Other Systems ?
instuNet is better than other systems for the following reasons:
instruNet is the highest-accuracy data acquisition system for performing low-level measurements
The instruNet card cage does not contain a noisy processor, which makes
it easier to do accurate low level measurements.
Low level measurements are required by many sensors, such as thermocouples,
strain gages and load cells; which respectively measure temperature, bending and weight.
instruNet is the lowest-cost data acquisition system with UNIVERSAL
Universal inputs support the direct connection to common sensors, sometimes with the
help of one additional shunt resistor.
instruNet does this at $124 per-channel with an 8-channel system, with unprecedented accuracy.
instruNet is the lowest-cost CARD CAGE data acquisition
Card cages enable one to mix and match modules as needed.
instruNet is the lowest-cost data acquisition system with optional anti-aliasing
Anti-aliasing filters eliminate errors caused by high frequencies that enter the digitizer,
as explained here.
i4xx Series Data Acquisition Cards
Communications card connects an iNet-400 card cage to a Windows computer via an instruNET iNET-240 USB controller
Provides 20 single-ended (SE)/10 differential (DI) voltage input channels and 4 universal digital I/O
Provides 6 differential (DI) voltage input channels; each of which has its own amplifier and low pass filter
Provides 16/8 DI/SE voltage input channels with a 16-bit A/D converter, 4 voltage outputs, and 4 digital I/O
Provides 12 universal digital I/O (20 mA sink, -10 to 30 V)
and 16 digital I/O (200 mA sink, -10 to 30 V)
Optional Anti-Aliasing Filter
optional 8-Pole i500
analog low pass filter daughterboard is ideal for
For a summary of aliasing and why you might need an AFS filter, click
The i500 provides extremely low ±0.01 dB maximum passband
ripple for Fin/Fc ≤ 0.5.
If one uses further
oversampling, digital filtering and
desampling; then passband ripple
is ±0.002 dB for Fin/Fc ≤
0.8 due to the accuracy of a 30-pole digital filter.
The end user installs between 1 and 6 filter daughterboards onto each
i423 card, one per channel.
For details, click here.
instruNet includes software to interrogate, test, configure, and do I/O with all network channels.
This includes an application program called "instruNet World" and interfaces to Visual Basic, C, and C++.
instruNet software can configure all I/O channels, store your settings, view digitized data in real time,
stream data to disk, and scroll through your waveform post-acquisition.
instruNet software runs on Windows computers.
Free software and manual updates are available here.
The table below shows which sensors directly connect to each hardware product.
The numbers in the table refer to number of channels; and if you click on those numbers, you will be redirected to the
measurement accuracy for that sensor and product.
The following sensors require an external shunt resistor:
RTD, thermistor, resistance measurement, current measurement, ¼ bridge strain gage, and ½ bridge strain gage.
Thermocouple sensors require an i51x Wiring Box
attached to the i4xx card 28.
In order to do voltage measurement, one needs at least one i430 A/D card. One only needs one
i43x a/d card per card cage.
instruNet i4xx cards are installed by the end user into an
instruNet card cage that is 4, 8, 12 or 16 slots wide.
Each card is 13 x 2.5 x 13 cm in size. Below is a list of available cards. For more details on each, click on the model number in the below table.
For details on the i555 Starter System, click here.
Low Noise facilitates High Accuracy
We obtain high accuracy by placing the noisy microprocessor
in an external box, away from the signal conditioning
amplifiers in the card cage; as illustrated below.
The below picture shows the i430 card digitizing 0 Volts at a 1K sample-per-second rate
on it's +-10mV range with 2.5 microvolts RMS of internal noise (no integration).
To further reduce noise, one can digitize more slowly and integrate each point.
The below scenario is similar to the above, yet with 16 mSec integration per point at 60 samples-per-second
resulting in 0.2 microvolts RMS of noise.
Maximum Sample Rates
The following table shows maximum aggregate sample rates for
an i240 USB controller attached to an i4xx Card Cage.
To calculate the sample rate for each
channel, divide by the number of channels attached to the i240 controller. For example,
if the maximum aggregate sample rate is 166Ksamples/sec/controller, and you digitize 4 channels,
then you could digitize each channel at 41Ks/sec/channel.
For more details on this table, click here.
One can attach up to four i240 controllers to a computer to increase total system throughput.
Max Aggregate Sample Rate per Controller (K samples/second/controller)
i51x wiring boxes easily bolt to i4xx cards.
The i510 is the simplest and is included with the i555 starter system.
The i511 includes 8 bnc connectors.
The i512 has a vRef/2 source that is used to help complete
1/4 bridge and
1/2 bridge strain gage circuits.
If you are measuring thermocouples, then the i510 is the only wiring box that will work, since it contains
an internal temperature sensor that measures the temperature of the i510 screw terminals.
For more details on each, click on the model number in the below table.
1/4 and 1/2 Bridge Strain Gage vRef/2 Support
Individual Banks of Screw Terminals for each sensor
The i400 product provides 4 slots, and multiple i400's can be bolted together
by the end user, side-by-side, to create an 8, 12, or 16 slot system.
In many applications, one i400 with 4 slots is sufficient.
Theory Of Operation
instruNet is a low-cost hardware card cage that attaches to Windows computers
via USB 2.0. The advantage of a card cage is one can mix and match modules as needed,
to build exactly what they need. The advantage of the instruNet card cage is cost.
For example, instruNet 4 to 16 slot chassis sell for $100 per slot, whereas comparable
chassis are 2x to 4x more costly.
The instruNet card cage typically has one A/D measurement module; additional modules provide signal conditioning. The conditioned analog
signal is routed to the A/D module via the backplane. This is dramatically
different from comparable systems, which place A/D measurement electronics on each module.
The advantage of the instruNet topology is cost. After the first module is installed,
additional instruNet channels are conditioned at approximately $40 per channel, whereas comparable systems typically cost 2x to 8x more.
The optional 8-pole i500
analog low-pass filter daughterboard provides very accurate
anti-aliased data at low cost.
Connect to Computer Via USB
Each instruNet Network is controlled by an instruNet i240 DSP controller card that attaches
to a Microsoft 32bit or 64bit Windows ≥ Xp Sp2, Vista, 7 or 8 computer via High Speed USB 2.0
at 480mbit/sec. Each i240 Controller is an independent computer in itself that utilizes a powerful
32-bit DSP processor and onboard RAM to control all aspects of data acquisition along its network.
All real-time tasks are off-loaded to this processor, therefore the host computer is not burdened
with real-time issues. Each instruNet network supports up to 4 instruNet iNET-400 card cages.