-
Similar Content
-
By paulofelora
I have a requirement that I thought would be SIMPLE, but can't get it to work. I have a 9205 card in a little 9174 cDAQ USB chassis.
My *intended* behavior is to wait (block) at the DAQmx Trigger/Start Analog Edge on, say channel ai1, until I get a falling edge thru, say, -0.050V. So I have a little vi (that contains 2 parallel loops) that I want to sit & wait for the trigger to be satisifed. I'm doing "routine" voltage measurements in another AI loop on a different channel. I want this vi to run separately from my "routine" voltage measurements because I want the app to respond "instantly" to input voltage exceeding a limit to prevent expensive damage to load cells. I was afraid that if I used either Finite or Continuous sampling to "catch" an excessive voltage, I might miss it while I'm doing something else. Yes, yes, a cRIO real-time setup would be better for this, but this is a very cost-sensitive task... I just want to "Arm & Forget" this process until it gets triggered, whereupon it fires an event at me. SO... I'm also reading the same voltage on channel ai0 for regular-ole voltage measurements, and just jumpering them together. I did this because I read somewhere that you can't use the same channel for multiple DAQ tasks - I *thought* I would need to set up the tasks differently. {but now that think about it, the setups can be the same...}.
I've set up the DAQmx task the same as shipping examples and lots of posts I've seen. I'm supplying a nice clean DC voltage to a 9205 card using a high quality HP variable power supply. Using NI-MAX, I've verified that my 9174 chassis & 9205 are working properly.
THE PROBLEM - When I run it, the vi just sails right through to the end, with no error, and an empty data array out. No matter WHAT crazy voltage I give the "DAQmx Trigger.vi" (set up for Start Analog Edge), it never waits for the trigger to be satisfied, just breezes on through as if it weren't there. If I set the Sample Clock for "Finite Samples", the DAQmx Read fails with timeout - makes sense, since the trigger wasn't satisfied. What could I possibly be doing wrong with such a simple task???????
So my fundamental misunderstanding still vexes me - does the DAQmx Trigger vi not block and wait for the trigger condition to be satisfied, like the instructions state - "Configures the task to start acquiring or generating samples when an analog signal crosses the level you specify"?
I stripped my requirement down to the bare essentials - see the 1st snippet, the 2nd is my actual vi. Any ideas, anybody?
-
By Zyga
LAVA users,
We are looking for alternatives for NI DAQ devices for industrial automation. Since NI has its devices mostly focused on advanced/high speed/high precison data acquisition/processing its prices are inadequate to simple automation tasks.
I would also say that NI PC based daq systems are expensive if need to be distributed systems (found this but still relatively expensive cRIO required).
Just now we need to extend our compactDAQ based system with two DIO modules. We even have free chassis slots for this, but station that needs this IOs is few meters away from PC. How easier would it be if we could use single ethernet cable.. Ofcourse we can add another small cDAQ (what we probably going to do) but this is slightly expensive solution for our customer.
Does anyone have some experience with 3rd party solutions? Any known daq devices vendors? Standalone ethernet daq modules?
Regards,
Zyga
-
By Gab
Hello Everyone,
Need some verification with daq program.
I have one force sensor that connectd with my usb daq device. with this force sensor, unknown object is connected(hanging) and i want to find the mass of this object (F=ma) so i am taking continous sample and generate waveform graph. After the scaling, my waveform will be in Newton unit.
my question is: if i take RMS of this waveform(1d Array data point) and divide by g (9.8 m/s2) then whatever value come is my correct mass? (F=ma).
Thank you in advance
-
By neunited
Dear All,
I'm new to this forum and I'm really glad I became a member.
I am currently in the phase of designing a simple program which can control all the DAQmx channels using a configuration file (.ini) which is capable of change voltage range during mid-simulation.
At the moment my .ini file reads as follows:
[AO Channel 1]
Name = T2
Physical Channel = cDAQ1Mod1/ao0
Max Value = 10
Min Value = 0
[AO Channel 2]
Name = T3
Physical Channel = cDAQ1Mod1/ao1
Max Value = 10
Min Value = 0
[AO Channel 1]
Name = T2
Physical Channel = cDAQ1Mod1/ao0
Max Value = 5
Min Value = 0
[AO Channel 2]
Name = T3
Physical Channel = cDAQ1Mod1/ao1
Max Value = 10
Min Value = 0
My LabVIEW VI for the .ini script is attached. I'm relatively new to using configuration file functions and I don't really understand where "Get Key Names" section should be wired to. I have placed a constant on it for now which reads the "AO Channel 1" but how can I get it to read all the channels in the .ini file.
I am welcome to all suggestions here, I just want to make sure that I don't cause any problems to any of the channels and use best practice methods. All constructive criticism welcome!
Thank you.
Read Configuration (INI) File (1).vi
-
By Atron100
hi
i have a question in basic understanding of update rate sample rate samples per buffer and cycles per buffer.
i have DAQ 6343 and electronic circuit.
i'm using AO0 for generation sine wave at these frequencies 10Hz, 100Hz, 500Hz, 1kHz, 3kHz this signal enters to electronic circuit.
and after conversion i must to measure two outputs of this circuit by AI2 and AI3.
from my understanding of tech spec of the daq analog output update rate is 900kS/s and analog input update rate is 500kS/s
as i understand if i have freq = 3kHz the maximum sample rate per buffer is 300 samples
and if i have freq = 10Hz i can generate this signal with 90000 samples per buffer?
for analog input the formula is the same?
that meaning of cycles per buffer?
which sample rate of AI i need to setup to measure data fast and accurately?
thanks for answers
-
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.