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Physics 434 Module 1

• About the computers:– You can save VI’s on the local disk.

• put them into My Documents\your_name• (But beware: no backup, no protection)

– Or just use catalyst for temporary storage!

• Review of last week – some important LV lessons– Controls, indicators, while (and for) loops, graphs– Right-click!– Tool options: auto, menu, or tab – Cntrl-b (remove bad wires, with care)– Cntrl-z (undo) – Shift-right-click: bring up the tool menu

Physics 434 Module1A

The next two weeks

• Introduction to DC I/O capability of the PCI-E board and use of the break-out box 10 V out, upto 8 measurement channels, also 10 V.

• Wire a simple circuit on a breadboard– Layout guidelines– Oscilloscope, DVM auxiliary tools

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The Pretest:-introduction to the circuit -diagnostic for us (written by Mac Stetzer of PEG)

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The “voltage divider” circuit

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dac0ach0

ach1

Physics 434 Module1A

R1 = 100R2 = 200

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Properties of the “DAQ” board

– up to 16 input channels, multiplexed to a 12-bit ADC • (we use four, configured as two differential)

– 2 output channels (2 12-bit DACs) (we use one)– Questions:

• what does 12-bit mean?

• Linear A vs. D: but what are the offset and scale factors?

• Can you control them?

• Differential vs. single-ended?

Physics 434 Module1A

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The PCI-MIO-16E-4 boardB

reak

out-

box

Com

pute

r

Physics 434 Module1A

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Differential input

Physics 434 Module1A

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Wiring to be done to the “Breakout box”

• Differential inputs: red/black pair to BNC– Input channel 0 (ach0): ACH0/ACH8 [68/34]– Input channel 1 (ach1): ACH1/ACH9 [33/66]– (beware touching the BNC connector to anything)

• Output: two wires long enough to reach breadboard– Output channel 0 (dac0): DAC0/A0GND [22/55]

• Note that while the inputs are “floating”, the output is not: it is relative to ground.

Physics 434 Module1A

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Testing: get the testio vi

• Click on the calendar entry; copy Module1.llb to your space; open it, then the vi test_io

• We rarely build vi’s completely from scratch: this is a framework, around a custom vi to do the I/O

Physics 434 Module1A

Features of the test framework

• Knobs, dials for the input, two outputs• A special test mode – an important feature for

experimental design• I/O put into a special sub-VI with three “frames”

– Set dac0 using a DAQ assistant– Delay (default 0) (allow system to adjust to change)– Read ach0 and ach1 with another DAQ assistant.– All set for -10 to +10 volts: you may want to change later.

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Procedure for this week

• Set the test mode of the test_io VI to produce outputs according to your expectation for the first pretest question.

• Revise the VI so that you can generate a graph like the one you sketched (see the graph example in graphdemo vi, or examine fig 8.17.)

• Wire up the board with the two resistors, and make connections to the breakout board, to correspond to the question. Neat layout is very important, for you to understand, and for us to help!

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XY GraphX InputY Input

XY Graph

Instance

Numeric

Example layout

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daco

ach0 ach1

Physics 434 Module1A

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Hints

• VI: keep neat, use labels and add comments• Test each piece first! You can have separate vi’s• Breadboard: Lay out the circuit neatly: use the space• If appropriate, test the circuit with power supply, DVM

or scope before trying to run the VI.• Keep good notes: a personal lab book is best• Use reference material• Ask a staff member

Physics 434 Module1A

Requirements for the VI

• Sweep through predefined set of values for setting V0 (perhaps a for loop)

• Record values for V1 and V2 for graphs and analysis, using either or both experimental or test modes.

• Plots:– V1 and V2 vs. V0: the data and your expectation (test mode) perferably on

the same graph, each labeled (so 4 graphs on the same plot) or two plots)– V2 vs. V1 (as in the pretest)

• Analysis:– Discuss the graphs and comment on the results– Measure and comment on the ratio V2/V1 and the sum V2+V1. (You may

want to have plots or at least some measurements)

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Turning in your VI(s)

• Operate | Make current values default – needed to record your results by saving the graphs

• File | VI properties | Documentation: write a little report, containing your name(s), purpose of the VI, implementation features, conclusions.

• Submit multiple VIs in an llb, like Module1.

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Next week’s circuit

Lamp Characteristic Test Circuit

V (10V)

IRF 511

R1, 22

Lamp

R0, 1M

D

S G Set the voltage here…

And measure the voltage and current here

The IRF511 power MOSFET Transistor.

G D S

Physics 434 Module1A