6008 connections

[waldoheriam]

I have a 6008 DAQ and need some help with connections... I think this is too simple of a question cause it looks like nobody has asked it before...

I have a circuit board which lights an LED when the events of the board set it off.
What I would like to do is have the 2v go to the DAQ instead of lighting the LED. My plan is to replace the LED with wires to the DAQ.

So with a mulimeter at the legs of the LED when it flashes I get 1.98V.


The Question is can I run the wire from where the LEDs + leg is to a digital input, and the -leg to the Ground on the DAQ?


The next question is, part two of my experiment will need a user signal via a switch. ?an I connect one wire to an input and the other to +2.5V and when pressed the switch closes the circuit?

thanks in advance for any help.

[mallorim]

Hi Waldoheriam,

Welcome to the forums! As I understand the first question, you have a circuit that turns on an LED using 1.98 V when an event occurs. Instead of the LED, you would like do use your USB-6008 monitor the event. To do this, you want to remove the LED and instead have two wires coming from the positive and negative leads. Is my understanding correct?

You asked if connecting the positive lead to a digital input and the negative lead to ground would be the best connection scheme. I do not believe that this is the best way to go. This is because the digital inputs use TTL logic, where a high measurement is only guaranteed if it is over 3.3 V. I think the better way to record this voltage is to use a differential analog input task and connect the leads to AI + and AI- of the USB-6008.

As I understand the second question, you would like your USB-6008 to read 2.5 V when a user closes a switch. Is my understanding correct? The set up you described would work, but I believe that you will want to connect one wire from the switch to AI+ of the USB-6008 and the other wire from the switch to positive lead of your power supply. The negative lead from the power supply will need to go to the corresponding AI-.

I hope this explanation helps, Mallori M.

[waldoheriam]

Thank you for the help Mallori,

I'll use the AI+ and AI- for the first part...I'll have to read up on differential analog input 🙂

But on the second part I just want the DAQ to know a switch was pressed (switch is seperate from the first circuit so I dont have a power supply to connect).  I was thinking to use the 2.5V from the DAQ 'cause I thought I needed a voltage to detect.  since the digital side needs 3.3v at least should I use the original plan but with the 5v pin on the DAQ?

[mallorim]

Hi Waldoheriam,

With regards to differential voltage measurements, you can look online in the Analog Input section of the NI USB-6008/6009 User Guide and Specifications. This shows you how to connect the signals, and then if you were using a test panel in Measurement and (MAX), you can select the differential as the measurement type.

So, the voltage is unimportant, it is the switch you want to monitor. Do you want to count how many times the switch was pressed or get times that the switch was pressed? If you want to count the number of presses, you can connect the 5 V pin to the switch’s input and the switch’s output to the PFI 0 pin as a source for a gated event counting. You can then run the Count Events LabVIEW example. If you need time information, you will need to connect the switch’s output to an Analog Input pin and perform a regular Analog read. This will give you time stamps that you can look at when the data is high. If you are in differential connection mode from the first application, then you will want to connect the card’s ground pin to AI-

I hope this explanation helps, Mallori M.

[waldoheriam]

Cool,

Thanks again for the help.

the switch just needs to be detected once and ignored if clicked again. 
The basic plan is ignore the switch if clicked before the leds blink. After they blink run a vi in a loop waiting  for it to click.  When it clicks run its vi and ignore any following clicks.


hmmm.... I just read that and noticed what it looks like.... I'm doing a lucid dreaming project not making an explosive device 🙂

[mallorim]

Just out of idle curiosity, what is a lucid dreaming project?

Regards, Mallori M.

[waldoheriam]

Well the plan is...use an eyemask which detects REM sleep.  When that happens the computer gets the signal to run the program, which basically says "hey kid don't wake up now, but you're having a dream".  At this point you should be able to control the dream. People can learn to do it without the gadgets, but I want to see if it can be done with the computer program and no lucid dream training.

lucid dreaming faq here...http://www.lucidity.com/LucidDreamingFAQ2.html

[mallorim]

Interesting. Well, good luck. 🙂

Mallori M.