Data Acquisition Hardware and Software
Introduction to the DAQ Box
The current data acquisition (DAQ) system of the METEOR family of projects was
developed by project 7110 last spring and will be modified by 8104. The present design
is given in the block diagrams on page 37.
The DAQ box obtained from P7110 is capable of gathering data from up to 6 load cells, 4
pressure sensors, 2 IR temperature sensors, and 4 thermocouples. The load cell outputs
are amplified with an op-amp circuit, amplifying the input with a gain of 333. The circuit
was designed and created on a PCB. Sensors directly connect to input ports on the front
panel of the DAQ box. To view the output waveforms, the DAQ box has four A/D
converters with RS-232 serial ports, which can be connected to computers. The A/D
converters are capable of gathering data from four different sensor inputs at the same
time. They measure with 10 bit analog resolution at a sampling rate of 240 samples /
second at one channel. Two channels will measure at 120 samples / second, three channel
will measure at 80 samples / second, and four channels will measure at 40 samples /
second. The measurement range is from -10V to 10V. The analog sample size of
measurement is 20 mV/bit.
Sensors
Three of the four sensor types require excitation from a voltage supply, namely the load
cells, pressure sensors, and infrared temperature sensors. Each sensors used will measure
at a different resolution. Specifications of the sensors will be given in the table below:

The load cells’ output is amplified by an instrumental op-amp so that the signal
size is larger, making for more accurate data collection. The initial output voltage
of the sensor is 30mV. The op-amp is powered by 18V using two sets of 9V
batteries.

The pressure sensors require 12V of excitation. The output sensor range is
approximately 0.5-5.5V. It is powered with two sets of 6V batteries.

The infrared temperature sensors require 12V of excitation. The output sensor
range is approximately 0-10Vdc.

The thermocouple inputs do not require an excitation voltage. They are connected
to a separate thermocouple DAQ box inside the project’s DAQ box. The
thermocouple DAQ box is connected by an Ethernet connection to an adapter
with a serial port, which is how thermocouple data travels to the computer.
Sensor Type
Model
Quantity
Maximum load
Output (V)
Resolution
(per bit)
Load Cell
Yuyao Pacific
Weighing PA6140
2
500 Ibs
10
1 Ibs
Load Cell
Omegadyne Inc.
LC105-250
1
1 kIbs
10
2 Ibs
Small S-Type
Load Cell
Omegadyne Inc.
LC111-25
1
40 kIbs
10
80 Ibs
Lateral Beam
Load Cell
Omega LCEB25
4
250 Ibs
10
.5 Ibs
Pressure
Transducer
Omega PX3031KG5V
4
10 kpi
5.5
20 psi
Pressure
Transducer
Omega PX3021KGV
1
10 kpsi
.003
20 psi
Inferred Sensor
Omega OS1362-V2
3
538 C
10
1C
Inferred Sensor
Omega OS1361-V2
1
204 C
5
.5 C
Goals for the Data Acquisition System
Modifications will be made to improve the functionality and usability of the DAQ box
and associated software. Current components and specifications of the DAQ box is
summarized in the table below. Some small initial goals include fixing loose wires, reordering and labeling the front panel ports in a logical manner, and fixing in place the
unsecured op-amp box and batteries. These will be mounted directly onto the box to
prevent them from shifting during transport or use and possibly damaging other DAQ
box internals. The wiring for the modified box can be seen in the block diagrams on page
38.
There will be hardware added to the DAQ box. Additional A/D converters may be
needed to accommodate more sensors. Two more A/D converters would accommodate
up to eight additional sensors, guaranteeing enough capacity for this year and beyond. A
dedicated load cell converter box may also be required.
The major software goal for the team is to switch from the proprietary software that came
with the A/D converters to LabView so that user-friendly GUI and DSP can be
implemented for the data gathering and processing that the team is required to do.
Desired functions of the LabView program will be real-time sensor output display, DSP
capabilities, and possibly a computer-controlled emergency system stop. Some of the
desired functions may be difficult to implement, and the final task will be determined as
the GUI is developed. The GUI may be implemented on a few machines to facilitate
viewing of the signals from the sensors. In the past it has taken several individuals
watching several screens to be able to view and interpret all of the incoming data fast
enough to shut down the test if sensors indicate dangerous conditions.
Component
A/C Converter
Standard 9V
batteries
Standard 6V
batteries
Op-Amp
Voltage Regulator
Resistor
Thermocouple
Data Acquisition
Model
DI-194 RS
Quantity
3
4
Purpose
Measures sensors to be displayed on a
screen through serial connection
Excitation voltage
4
Power op-amp circuit
INA114
1
AN78L12
AN79L12
Standard
2
DI-1000TC
1
Provides a gain of 333 at load cell in order
to view results on screen
Helps to maintain a constant voltage value
to power op-amp
Regulates voltage specifications to outuput
voltage gain of 333
Measures temperature through
thermocouples
1
Software design
Another electrical engineering task will be to create a GUI that will be able to display the
outputs of sensors on a user-friendly screen. These sensors will measure temperature,
pressure, and load. The signals of the sensors will be acquired through the DAQ box. The
GUI will be created via the software, Labview. The general layouts are given in the
following pages (Figures 1-4). Some features of the interface will include:





Obtaining signals through multiple serial ports to computer screens
Measure in real time
Capable of saving data after acquisition
Calibration feature
Emergency abort switch to shut down all operations
There are many ways of implementing the features above. Some design ideas include:
 Labview is capable of taking measurement in a variety of units, including data on
a time scale. This can be measured through setting certain properties in the block
diagram.
 Saving data after acquisition is possible by using a Write to Measurement File
function. There is an option of configuring everything in a pop up window.
 The load cells can be calibrated to accommodate for initial load. A constant could
be added into the current output to offset the transformation of the origin.
 An abort feature could be implemented through setting a property in the block
diagram. Labview has the capability of controlling hardware
Current DAQ Box Block Diagram
DAQ Box Redesign Initial Thoughts
Load Cell Interface GUI Interface
Pressure Sensor GUI Interface
Inferred Temperature Sensor GUI Interface
Thermocouple Sensor GUI Interface
Appendix A: Yuyao Pacific Weighing PA-6140
Appendix B: Omegadyne Inc. LC105-250
Appendix C: Omegadyne Inc. LC111-25
Appendix D: Omega LCEB-25
Appendix E: Omega PX303-1KG5V
Appendix F: Omega PX302-1KGV
Appendix G: Omega OS136-2-V2
Appendix H: Omega OS136-1-V2