Discrete signal to a continuous signal

Hi to all,
I'm having this problem with the signal processing, and I hope you could help me...
I have a discrete signal, that is a capturated with a PIC controller. Now I need that this signal become a continuous signal, so I can use a lot of other VI that I can't use when I have points.
How can I transform the discrete signal in a continuous one?
Thanks in advance,
Ricardo.

Hi,
I don't know what you mean exactly. A solution to yopur problem might be just to build an array with your points. To do that you can use the LabVIEW function called build array.
Hope this help.
Regards,
ClémentG

Similar Messages

Continuous output voltage at DAQ board delivers undesired discrete signal

I am attempting to output a continous decaying signal as seen below.
(For the time being, assume that I must leave the sampling rate at Fs: 1000 and #s: 1000.)
In the loop where the signal is generated, I inserted a 'Wait (ms)' block so that the iterations would maintain the correct timing. If not, the speed of the iterations would be too fast. Although, when I measure the output at the BNC connector, the actual output is in discrete steps, which depends on the speed of the iteration. (e.g. for the above signal with freq = 1/4 Hz, the output would remain 1V for two seconds, 0.5V for one second and 0V for one second, then repeat)
Is there any way to fix this?
Before I attempted this method, I had used the DAQ assistant output, which did not require me having to insert the 'Wait (ms)'. But, the problem with this method was that there was a delay between the time the program sent out the signal and when the BNC output connector received the signal.
I assume the second method did not output in discrete steps because of the buffer which is maintained in the assistant. I attempted to have some sort of buffer for the first method, but was unable for lack of experience I assume. If I was able too, it seems that I might introduce a delay once again, which is undesireable.
Any help on this topic would be appreciated. I will attach a copy of the section that is giving me trouble.
Thanks.
Mike
Solved!
Go to Solution.
Attachments:
Voltage Generation.vi ‏122 KB

Mike310 wrote:
Thanks for the advise Mike.
At the moment, I went back to using the DAQ express, since the signal, while using the same sampling rate, appears nearly continuous on an oscilloscope. Although, as I mentioned previously, this introduced a problem with the signal output at the board being delayed by a few seconds. To compensate, I wired the generated signal to a delay before entering the 'write file to spreadsheet.vi', so that the input signal, which was a result of the generated signal, and the generated signal, would be synchronized on the saved file.
The fact that the DAQ express is taking a few seconds must mean it is doing something to condition the voltage. Without really wanting to know what goes on inside the express VI, I would guess that it actually samples at a much higher rate than you specified to give it a smooth ramp, but keeps the external clock at what you did specify.
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

Discrete signal recognition from continuous waveform

Hi Folks,
I'm hoping some of you can give some general pointers on how to better approach this problem. This is the first application I will be actively performing waveform analysis so forgive the amateurishness.
Anyway I'm acquiring a physiological signal at 50Hz and attempting to recognize 'breaths' from this source. The problem is that the frequency, amplitude, and offset will vary depending on the rate and depth of breath (among other things). Below are the ranges I'm working with (in units of "WC pressure):
Freq: 10mHz-500mHz
Amp: 0.005 to 0.145 "WC
Offset: -0.25 to -1.0"WC
In general, I'm trying to reliably get a measure on each breath's amplitude (and offset, but that's easy) and frequency. I have tried two methods: to isolate each breath and analyze, or to buffer say 10seconds worth of signal and analyze. The problem mostly comes in when I try to use the "Pulse Measurements" and "Amplitude and Levels" vi's as part of the analysis package. The way in which they perform their calculation relies on set crossing thresholds - if the signal jumps in amplitude or quickly changes frequency (not likely) and I'm using the buffer approach, I lose calculation on the buffer. Obviously using a fixed buffer size (can) give different results depending on the frequency of the signal.
It's amazing how we (as humans... right?) can discern the breaths from this signal, how we can easily identify problematic shapes, but to do this programatically, it's a completely different story.
I'm just unsure how to better approach this - should i be trying to fit an ideal curve to every group of samples? Attached is a screenshot of ideal (at two distinct rates) and actual.
Message Edited by 8bitbanger on 07-10-2009 02:19 PM
v2009 devel. w/RT
Attachments:
inWC_actual.PNG ‏44 KB
inWC_ideal.PNG ‏43 KB

First, I would filter out the small quick changes is the waveform (unless they are significant to what you are doing or you consider them to be a breath).
In the past, I have tried to heavily filter respiration down to a sinusoid signal and then take the Hilbert transform to create an analytic signal (f(t) + jH{f(t)}). Take a look at the derivative of the phase of this signal which is equivalent to its instantaneous frequenc.
Take a look at attached. I saved data into the Data In control for you to use as an example. This data is monkey respiration, so it is a little faster than human. Play around with the filters to see what is best for your data. Hopefully, this will be of some help.
Randall Pursley
Attachments:
Resp Rate.vi ‏269 KB

Y/t - graphic: discrete values are displayed continuously

Whenever I want to display discrete values in a y/t - graphic, they are displayed continuously (adjacent function values are connected)
See for example:
The lower graphic should show the following discrete function:
x | (fx)
---|--------
2 | 0
3 | 1.27
4 | 0
5 | 0
6 | 0.64
7 | 0
8 | 0
9 | 0.42
But as you can see, adjacent function values are connected. I couldn't find out, how I can change that. Hope someone can helb me!
thanks,
Philipp
Solved!
Go to Solution.

Excellent question and documentation! Thank you for making it very easy to answer your question.
Click on the Paintbrush icon on the Y/t chart display - this is a link to the Colors and Lines properties for the chart display. Select Bar from the drop down list for Input 0.
If you prefer a discrete symbol, choose from cross, square, circle, etc.
- cj
Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab.

Continuous signal to discrete

Hi everyone,
I'm supposed to do a discrete time fourier transform (DTFT) for my input signal.
I got the input signal from "Basic Function Generator.vi" which is suppose to be a continuous and periodic signal. With respect to DTFT function, the signal has to be discrete and non periodic.
Now the question is, how to I convert the continuous signal to be discrete, and how can I make the signal non-periodic?
Thanks a lot in advance.
Solved!
Go to Solution.

Hi,
When you generate the waveform with the vi, it is already a discrete and non-periodic signal.
It is a discrete signal because the function is not defined for all time, but only at the multiple of your sampling period, i.e. you only have data point at the sampling period intervals. If you have a sampling rate of 0.1ms with initial time =0, you would have a point at 0, at 0.1ms, at 0.2ms, at 0.3ms, etc, and you will not have any data point at 0.05ms, 0.25ms, etc.
It is a non-periodic signal, because at any given time, you would only have a waveform from a particular time instance to another particular time instance, and you will never have a waveform form from -inf to +inf, which is part of the definition of being periodic. Let me know if this is clear or not.
Yik
Kudos and Accepted as Solution are welcome!

Discrete to Continuous.. how?

Hi to all,
I'm having this problem with the signal processing, and I hope you could help me...
I
have a discrete signal, that is a capturated with a PIC controller.
Now I need that this signal become a continuous signal, so I can use a
lot of other VI that I can't use when I have points.
How can I transform the discrete signal in a continuous one?
Thanks in advance,
Ricardo.

Yes, maybe you did not run the VI before changing the indicator to a constant, thus it is an empty array. Your indicator must contain data first before turning it into a constant ..
Of course it is possible that versao7subVI (not included with your code) gives empty arrays once in a while (e.g. in the later loop iterations). You seem to rattle through many iterations of the FOR loop at full speed, so you might easily miss early iterations that produce good data. Sorry, I don't quite understand your code.
LabVIEW Champion . Do more with less code and in less time .

How to simulate discrete fourier transform using CMOS on multisim11.0

Please tell me how to simulate discrete fourier transform(DFT) using CMOS implementation in Multisim 11.0..

vlsi,
If I am reading your question correctly, I think this is more of an issue of IC design rather than how to use Multisim (the circuit you describe is likely very complex and would involve many CMOS/transistor components). If you have an existing or partial circuit already ready to start with, the group could better assist with how to implement or use in Multisim for simulation. Although it is possible to model a comlex digital parts with CMOS equivalent logic and gates, most of the more complex digital parts in Multisim are modeled in XSPICE, which allows the behavior to be described by a truth table and timing descriptions and the pins are modeled in SPICE.
However if you want to use a predefined DFT algorithm inline within a circuit simulation, you can likely use with a custom LabVIEW VI, we have several Fourier Transfer algorithms in which you could process a signal coming from a circuit simulation in which the transform and simulation could be run together.
http://zone.ni.com/reference/en-XX/help/371361B-01/lvanlsconcepts/discrete_fourier_transform/
There is an example of how this can be done with an FFT (which is a type of DFT)
https://decibel.ni.com/content/docs/DOC-7438
Another idea is to use our co-simulation technology in Multisim v12 together with the LabVIEW Control Design tools. The LabVIEW Control Design package has several discrete signal processing algorithms built in and you could use them together for very precise mixed signal co-simulation between an electrical simulation and a discrete processing algorithm.
http://www.ni.com/white-paper/13663/en
Regards,
Pat N

I have transefer function like (1/(s^2+s+5)) and i have a square wave input , i want to use this transfer function with this input to see the output , how can i do that , with example please.

i need to know also how to represent this transfer function in labview, try to send me example. answer me at my mail

"st" wrote:
> answer me at my mail
give a valid e-mail first, and your name, we don't like to help anonymous
people
> try to send me example.
how much do you pay ?
> i have transefer function like (1/(s^2+s+5)) and i have a square wave
> input , i want to use this transfer function with this input to see
> the output , how can i do that
First you have to know what you are doing, like an engineer : you have a
Laplace, continuous time transfer function but LabView handles discrete
signals only. Use matlab/simulink if you want to simulate continuous time
systems easily...
If you definitely want to use LabView, the first step is to discretize your
continuous-time transfer function, i.e. decide a sampling rate and convert
it to a "z transfor
m". Then you can directly use the "IIR Filter.vi" as I
said earlier.
Philippe Guglielmetti - www.dynabits.com me at my mail

Timeout in NI-1772

I have set up a Smart Camera (NI-1772) in an grading system which is used to measure and count product fed passed the camera by a conveyor system. The prodcut is sized by length, (by the camera ) and a PLC actuates mechanism that put the product in the correct boxes, The PLC senses Discrete signals from the Smart Camera. I have set the PLC to do the counting and the Camera read the counts registers via modbus, the counts are displayed using “Overlay Function” on a monitor connected to the VGA output of the Camera.
I have a through beam sensor, that is used as a trigger the camera to take images.
Everything is working great, almost all the time. But there are times, usually after the camera has been sitting idle for longer periods of time (usually 5 mins or more) that the camera seems slow to act on the first trigger signal, and everything seems to be delayed as a result. (any triggers shortly after that seem to work fine) The screen is delayed being updated and the output to the PLC is delayed as well.
I’ thinking that this is a result of timeout in the trigger of the camera, which I have set to 5000ms. But im not sure about this.
My logic is basically,
If triggered take an image -->measure objects --> if there is an object detected--> update discrete output--> read modbus registers & update screen-->end
If it timeouts--> read modbus registers & update screen -->end
Do you see any problems with this aspect of the logic, ideally once a timeout occurs I would have no code between the timeout and the end, but I had to come up with a way to update the screen, when there were no triggers.
How much delay would you think reading 7 modbus registers and updating the screen would take?
I can provide more information or code if required.
I appreciate any assistance you can provide.

Thanks for you reply.
I have tried the timeout really short, and I seemed to get more frequent problems,
and I have tried it really long and I seem to get less frequent problems. Although the problem is infrequent in general.
However, If the time out is really long, (based on the code I have) the screen doesn't update as fast, as the screen only updates when it times out.
The reason I wanted to update the screen is when there are no triggers is; I wanted to display all the relevant information on one screen (counts and image).
I have 3 different sizes and 2 boxes for each size. So the camera sends the discrete signals to the PLC, the PLC waits the correct amount of time and moves the actuator to put it in the box. When one box is full (count =100) the PLC starts filling the other box(for that size).
This way the conveyor doesn't have to stop when any one box is full. There are reset buttons (6 in total) that the operator presses once a full box has been replaced with an empty one, so the PLC knows that it can now fill that box. If I let the camera do the counting, I would have to allow the camera to sense the reset signals from the operator.
So for simplicity and lack of I/O on the Camera I let the PLC do the counting and I send the counts back to the camera (soley to display on screen) via modbus signals.
I don't see any other way for the camera to read these modbus values and update the screen (other than following a trigger or timing out). I wouldn't have thought that reading 7 modbus registers and updating a screen would induce a long delay, but something seems to be.
But I will try, for a test, removing the code following a timeout so that the program executes a timeout as quickly as possible. And I will see if the problem goes away.
Then I will know for sure the problem is a result of delay induced from code being executed following a time out.
If this is the problem;
I could install a PLC display to read the counts via modbus from the PLC, then there wouldnt need to be any code following a i timeout.
but I would prefer to have everything on one display.
Thanks
Chris

NationalInstruments.Analysis.Dsp.SignalProcessing.Integrate method

Could you give me an example use of the NationalInstruments.Analysis.Dsp.SignalProcessing.Integrate method? I want to integrate a signal but I am not sure what to use for the boundary conditions (initialCondition and finalCondition).

eja,
The intialCondition and finalCondition inputs are to reduce error in the integration routine. Because you are taking an integral of a discrete signal, there will be some error at the signal's endpoints if you don't define these inputs. The amount of error will depend on the number of samples that you have.
For instance, If you try to take the integral of the array (1,1,1), with a dt of 1, and don't define intialCondition or finalCondition (i.e. set them to 0), the function will return 2.7, when the actual value should be 3. If you define initialCondition and finalCondition as 1, the function returns the correct value.
From the Measurement Studio help:
initialCondition and finalCondition minimize the overall error by increasing the accuracy at the boundaries, especially when the number of samples is small. Determining boundary conditions before the fact enhances accuracy.
For more documentation on the integrate function, open the Measurement Studio help, and search the index for "Integrate method"
Josh W. | National Instruments | Applications Engineer
Message Edited by Mist on 07-18-2006 03:17 PM
Josh W.
Certified TestStand Architect
Formerly blue

Accessing Parallel Port Control and Status Registers with VISA and Win7x64

Hello all,
I've posted this in the I/O forum for VISA, but this main forum seems to get a lot more traffic so I'm posting here too.
Wondering if anyone has a solution for accessing the Control and Status registers on a parallel port with VISA, now that Win7 has locked down the I/O ports and In Port.vi and Out Port.vi don't work anymore. I've been looking all over for a solution and haven't found anything that will help; either the VISA solution is shown but doesn't mention if the Status and Control registers are accessible, or the solution is for a 32 bit system.
The one thing I found was under Instrument I/O>VISA>VISA Advanced, there is a group of functions called Register Access; but, when I investigate that, it seems to need an address that the detailed help describes as "VXI, VME, and GPIB-VXI" or "PXI" with no mention of Parallel Port usage, so I'm pretty much at the end of what I can figure out.
Basically what I need to do is use the data lines to send info, and watch the status lines for incoming discrete signals. Since parallel ports are half duplex, I can't have the data lines be both inputs and outputs simultaneously, which is what I need. A cheap D I/O card would be the easiest solution, but to make a long story short I'm dealing with a legacy system and that's something my higher-ups want to avoid.
Any help is greatly appreciated!

Hello,
I was able to solve this problem using software from Entech Taiwan; it's called TVicPort and it's available for free for personal use, and very cheaply for commercial license. If you have questions let me know, I'll do my best to answer them but investigate Entech's solution and see if it'll work for you:
http://www.entechtaiwan.com/
http://www.entechtaiwan.com/dev/port/index.shtm

PXI 6512 to PXI 6511 using SCB-100

Hi;
Using LabView 8.6, I want to pass a discrete signal from a PXI 6512 (DO) to a PXI 6511(DI).
Each of these cards have a SCB-100 connector block. I have set the switches (S1 to S6) of each card to "DIO passthrough" as specified in SCB-100 Installation Guide Figure 3.
I'm using the following NI examples: Write Dig Chan.vi (running on 6512) and Read Dig Chan-Change Detection (running on 6511)
1. I have connected the PXI 6512 SCB-100 pin #1 (Port 0 Line 0) to PXI 6511 SCB-100 pin #1 (Port 0 Line 0).
    Result: I does not work; that is:
                                          a) Changing voltage on 6512 is not detected on 6511 vi
                                          b) Changing voltage on 6512 MAX is not detected on 6511 vi
2. I have a connected both pin #1 to pin #1 and pin # 9 (GRND) to pin #9 (GRND), doing the same as above (1.a and 1.b) , it still does not work.
3. To make things worse, I put a voltmeter on the SCB-100 pins of 6512, no voltage is generated.
I wonder:
    - How to connect two SCB-100 connectors for my case? is there something special to do in addition to setting the switches ?
    - How can I be sure using MAX that my cards are OK?
    - What are the correct driver versions (is it "traditional DAQ driver"?) for my cards?
Thank you in advance for the replies;
Kizkas.

Hello KizKas,
When performing the write to the digital channel, have you tested other lines other that Port 0 Line 0? Have you tried using a different breakout box, or a different cable? Have you double-checked all of your connections? If you could try all of these steps and measure the voltage on the line using a voltmeter you should get more information on what is wrong with your system.
The only steps you can perform in Measurement and Automation Explorer (MAX) to check to see if everything is working with your system is to first check to make sure that the icon next to your device under My System»Devices and Interfaces»NI-DAQmx Devices is green.
Figure 1: Green is Good
You can also attempt to reset the device or perform a self-test on the device itself by clicking on the device and clicking on the appropriate buttons.
Figure 2: Self-Test and Reset Device
For these devices the correct driver to use would be NI-DAQmx 8.8.
Message Edited by Dan_K on 12-03-2008 11:01 AM
Regards,
Dan King
Attachments:
buttons.jpg ‏9 KB
devices.jpg ‏38 KB

Audigy 2 zs and logitec z

Hi there,
I can't seem to figure out which digital cable to use to connect audigy 2 zs and my speaker system (logitec z680). the speaker system has a option of digital coaxial and optical output but the sound card doesn't have coaxial or optical ports (why wouldn't this sound card have coaxial port when most entertainment media has it's?).
My speakers work (for most part) with analog cables, but i want to enjoy the actual digital experience thats meant to be with these speakers and this card but it appears that i can't. Can you plz tell me what to do because with analog cables, either my center speaker doesn't work or if that works, other speakers don't work. Can you tell me which digital cable should i use? because for some reason, not many people know which digital cable you have mentioned in ur user manual.
I am really fed up because i just spent over $500 in total and i can't enjoy all the quality of this speaker system and the soundcard that makes up the price.
thank you

Hi there
If you are looking to use the coax then you need the converter (mini plug to female RCA). I'd be amazed if Creative couldn't sell you one. I got one as part of my GD580 pack. I think it is a special mini-plug though specific for this job.
Word of warning on the coax digital if you do hook it up - no good for gaming. You need the analogues for the best gaming sound (EAX doesn't come through digital SPDIF - only stereo through the SPDIF believe it or not). The coax digital should do you for DVDs and similar DD5./AC3 encoded material but only if you set the SPDIF to passthrough and allow an external decoder to take care of converting to the 6 discrete signals.
The question is therefore which has the best decoder - the Audigy or the z680? I don't know the answer to that but knowing the agony I've just been through with my GD580, I'd recommend sticking with the analogues. I'm upgrading my system to do exactly that. If you were going to a decent Home Theatre decoder/amp with the digital signal then that may be one case where the digi out from the card would be of use.
Hope that hel
ps.

Problems on reading PCM into digital form

Hi,
I'm now on a project doing heart rate detection.
Due to the project just started, therefore I do not got any device to measure my own heart rate, but I will be making up some PCM(analog) data, and try to read that into digital form and give me results of the heart rate.
I'm not sure am I on the right track now or not,
what I'm doing now is trying to convert a ".wav" into bytes array, then it should give me some data, however, I'm not sure how to relate that data into heart rate.
Please leave me any comment if u think it might help please.
Thanks,
till

I'm not too sure what should be the .wav should be, however, according to this acticle I got it from the web:
_2.1 Signal acquisition_
ECG signal frequency content lies between about 0.05Hz and
500Hz and has amplitude of few mV. The acquisition is provided
to be performed in three different ways: (i) using direct electrode
measurements, (ii) using ECG equipment with analogous output;
and (iii) using ECG equipment with digital output. For the first
two cases, a sampling rate of 8 kHz is assumed. In the third case,
the acquired discrete signals are accordingly resampled.
_2.2 Modulation_
The bandwidth of the phones voice channel is limited to the
range 300Hz-3300Hz. The signal amplitude at the microphone
input should not exceed 100mV. Modulation is performed through
multiplication with carrying sinusoidal signals. Five 500Hz-wide
channels are packed within the 500Hz-3000Hz band. The
resulting signal is appropriately refined in amplitude and directed
to the modulators output.
_2.3 Digitizing, storing and sending_
The complex signal is band-limited to 3300Hz. Therefore, a
standard sampling frequency of 8 kHz is used for its digitization.
A JAVA application performs that and in order to store the signal
intact, the signal is recorded in a lossless format such as pulsecode
modulation (PCM). The WAV audio file format implements
PCM and is used to store the recorded modulated ECG signals.
Once stored, the signals can be visualized, processed and sent by
the mobile phone.
Mobile phones firmware is accessible by programming
languages as C++ and JavaTM. Most mobile phones support
JavaTM runtime called Kilobyte Virtual Machine (KVM) [6]. This
language provides the ability to build a GUI application that could
support all the stages of recording, storing and transmitting of the
ECG signal. JSR-135 contains libraries of JavaME, which are
useful for capturing audio from the microphone's port of a mobile
phone. The above mentioned platform was used to create the
application software.
_2.4 Demodulation_
The procedure of demodulation is performed at the physicians
phone, following the reverse track of modulation. A digital band
pass filter is used to separate the spectra, corresponding to the
individual ECG signals. The filtered signal was then multiplied by
the corresponding carrier frequency and filtered with a low pass
filter, resulting in the original signal. The demodulated signals can
be stored in separate WAV files in the physicians phone.
_2.5 Matlab simulations_
In order to prove the principal feasibility of the approach, the
signal acquisition, processing and transmission procedures were
simulated in MATLAB. Five preliminary recorded ECG signals
were directly loaded and used. The signals acquisition parameters
were: 8-bit values, sampling rate of 250Hz and duration 10S.
Modulation and demodulation were programmed and performed
in a numerical way. Modulation was done by multiplication of the
ECG signals with carrying sinusoidal signals of frequencies
500Hz, 1000Hz, 1500Hz, 2000Hz, and 2500Hz. The
demodulation included first separating the spectrum of each
individual signal with the help of 4-th order 400Hz-wide bandpass
Butterword filters centered on the corresponding carrying
frequency. Next the filtered signals were multiplied with the same
carrier signals and eventually filtered with a low pass 4-th order
Butterworth filter (fc=200Hz).
btw, the system need to be implement into Symbian phone at the end,
but I'm just now testing on the PC atm =)
according to this article, what kind of wav I should be using ??
thanks a lot!!!

Accessing Printer Port with Windows 7

Hello all,
I've been recently asked to port a Labview file from WinXP (x86) to Win7 (x64), and one of the problems I've come across is this infamous lockdown of I/O ports in Win7. I've done lots of searching around but haven't found much that would seem to help me in my situation, so I thought I'd post and ask for your help.
Basically, yes, the parallel port is being used as a poor man's DIO in my situation; we're using the individual bits as discrete signals that can be either high or low to communicate between two computers; one is Windows, one is Unix. We used to use cviVXDwrapper.dll to do this, but that is no longer working. All I need to do is flip individual bits at the right moment, it's not banging any data through or actually adhering to any communications protocol.
I know that the easiest solution here would be to buy a cheap DIO card and call it good; at a matter of fact, I recommended that to my supervisor. But he came back saying that "all the drawings would have to be changed" and there would be "a mound of cards to be bought" and we'd have to go through all these design revision change review boards...so, if there's any way to find a software solution instead of a hardware one, it would be easier and less time consuming.
I can't give my entire .vi because of intellectual property/security concerns but I can provide a few screenshots that show just how simple the code is; we're literally just reading individual pins on the Parallel Port. Is it really that difficult to do this now with Windows 7 and Labview?
Attachment Notes:
1. to_printer_port.jpg - Here we have a simple snippet of code that, if the boolean value coming in is true, writes to bit 1 of the printer port. If that output is high, it lights up an indicator on the front panel called "FPGA Config".
2. from_printer_port.jpg - Another simple piece of code that reads a Printer Port pin and reports back in boolean whether it's high or low.
Attachments:
to_printer_port.JPG ‏14 KB
from_printer_port.JPG ‏10 KB

For anyone else searching around, I was able to find the solution!
Check out this link to the NI Developer's Website:
http://sine.ni.com/devzone/cda/epd/p/id/4213
It has an example of using VISA resources to write to the Printer Port. My guess is that to read you'd just swap out the write block for the read block (found under the Instrument IO/VISA area of the Function palette) . Also note that pins 11 and 12 of the printer port *MUST* be grounded to keep timeout errors from occurring.

Discrete signal to a continuous signal

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