NI Home > Community > NI Discussion Forums

LabVIEW

Showing results for 
Search instead for 
Do you mean 
Reply
Member
mariomoskis
Posts: 127
0 Kudos

represent a digital input in labview

Hello, i am reading with my module in compact rio ni9401 a input digital signal, how could i see all that digital signal in labview?

thanks

Proven Zealot
mikeporter
Posts: 5,074
0 Kudos

Re: represent a digital input in labview

If I understand you correctly, it depends on how you have the acquisition configured, it can appear as a scalar boolean value or an element in a boolean array.

 

Can you explain a bit more what the problem is that you're working on?

 

Mike...


Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion

"... after all, He's not a tame lion..."
Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

[ Edited ]

Yes,i am reading the output voltage Vin at the next circuit with my ni9401, I recieve the voltage, and i input 0 when my voltaje is less than 0.8V and i have 1 when my voltaje is more than 2V. with this i would like to do a counter and to know how many times rotate one motor of dc which i have between my photodiode and one led which isn´t in the picture.

 

Sin título.jpg

 

my code in labview with the counter is the next:

co.jpg

 

Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

so,i want to represent the digital signal in labview while my code is running, and to know if my counter is working well

Active Participant
NIquist
Posts: 1,352
0 Kudos

Re: represent a digital input in labview

[ Edited ]

Just right-click on the wire coming out of your CRIO block and select "create indicator".

 

By the way, there is a boolean invert function.  You don't have to compare the value to false with the equals VI.

 

EDIT: You can also right-click and select "probe".  That will pop up a temporary display useful for diagnostics.

Using LabVIEW: 7.1.1, 8.5.1 & 2013
Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

ok,i  will try to do it on monday and i will say you if it works or not

thanks

Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

[ Edited ]

hi, to reprensent the signal, i made a waveform chart,but i have the problem that i can´t see all values since the bucle starts until it stops,i just can see 1023 values. how could i see all values? is there a way to represent the digital signal unused the boolean to(0,1)?i would like to represent the signal directly.

And i don´t know if i am counting all times that my signal is false, that´s why the signal which dio4 is recieving,has T=13ms, i guessed that if my dt in labview is= 4ms i didn´t have problems,but sometimes the signal which i am representing in my waveform chart,it isn´t perfect because it is sometimes 2 cycles false.like this: _-__-_-_-__-

i tried it with dt bigger as: 7ms or 10ms but i have the same problem

how could i solve this problem? because i wouldn´t like to change the dt of my labview code when the signal which i recieved in dio4 has different period

is there in labview some option to change the function boolean to (0,1) to (1,0)?

Dibujo3.JPG

 

thanks

Active Participant
NIquist
Posts: 1,352
0 Kudos

Re: represent a digital input in labview

OK, it sounds like it's time for you to take some LabVIEW tutorials as these are very basic questions and you need to understand the basics before you can make good use of LabVIEW.  http://www.ni.com/academic/students/learnlabview/

 

Now your questions:

The waveform chart defaults to a history length of 1024.  Right-click the chart and change it to be longer if you need.  A long history will just cost you memory so you can make it pretty big.

 

Of course you can have a BOOLEAN indicator.  Just drop an LED on the front panel and wire its terminal to the point you want to monitor like I already told you. :smileywink:

 

WHY are you making your timed loop run SLOWER (4 < 7 < 10 < 13) if you want FASTER resolution???  Set it to 1mSec.  (Also, there are better ways to do this depending on your hardware but I'm not familiar with your DAQ.)

 

You can INVERT a BOOLEAN with the INVERT function found in the BOOLEAN palette!  Again, if you don't know these basic things, you need to take some tutorials to use LabVIEW.

 

Using LabVIEW: 7.1.1, 8.5.1 & 2013
Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

thanks

i did run my time loop at 1ms, when the speed is high there aren´t problem,but for example when the signal which is recieving dio4 has more than 2 ms in the false case,i have the problem that my counter increase 2 times,because it is reading the false signal 2 times! is there a way to don´t have to change the dt in my time loop when i have this case of slow speed? and how could i know that dio4 is reading the same frequency and my counter is working well?

Member
mariomoskis
Posts: 127
0 Kudos

Re: represent a digital input in labview

[ Edited ]

i am generating one signal TTL in my wave generator, trying differents frequencies and later trying to watch it with my code in labview

maybe it could be a good way to check if my dio4 is reading well the frequency.

but i really don´t know how to link the frequency which i am giving to my signal generated in my oscilloscope with the dt in my time lood of labview