Multiple inputs in NI usb 6008

I have to measure phase difference between two analog input signals. I did this by using two Ni daq assisstants but at a time I could only read one and an error comes. Kindly help me with examples if any of you have them.

The DAQ Assistant has the (evil) Dynamic Data Type as its output, regardless of the form of the ouput. If you actually have both channels in the data (an apparently you do because the graph shows them), then try Split Signals from the Express >> Signal Manipulation palette.
Or, replace the DAQ Assistant with the standard DAQmx VIs which allow you to choose arrays or waveforms as the output datatypes.
Lynn

Similar Messages

How can i connect 24VDC to digital input (usb 6008)

hello,
how can i connect 24VDC to digital input (usb 6008), is it possible with some optocoupler?
thanks

The 6008 is a static DIO, so speed shouldn't be an issue. Therefore an optocoupler should work. Just make sure you get one the meets your specs.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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USB 6008 doubt on channel inputs

Hi,
I would like to control a switch on AC to AC converter circuit i.e.. I want to blank signal in circuit until user interested time. I am just worried about DAQ at channels that can I directly connect 240v AC to DAQ or in case if not possible, I would like convert this 240V to 20V because, I read the datasheet of USB 6008 says that allow only +or- 1 to +or- 20v. I strucked here and could not conclude my self. Is there any best converters out there in market for this application?

Definitely do not connect 240 VAC to your DAQ card!!!!!!
You could look at a relay that has contacts rated for your current and voltage of interest. You could also look at a solid state relay that can take a low voltage digital signal to turn on and off the high voltage AC signal. But you will have to see the requirements for the input coil of the relay, or the input of the solid state relay and see whether the USB-6008 can source that voltage and current. If not, you may need to look at another circuit such as a transistor driver to turn on and off the relay.

Input Capacitance of the USB 6008

Does anybody know the input capacitance of the NI USB 6008? Im creating a circuit that mimics a 10x probe whose design requires the value of the "oscilloscope" input capacitance, or in this case, the USB 6008 input capacitance.
Thanks so much!

With the low input resistance (144 kohms) the capacitance does not matter much. Any realistic value of input capacitance will have a time constant shorter than is meaningful for the device bandwidth.
Also note that the input impedance is terminated in about 1.4 V. See the circuit in Figure 7 of the User Manual.
Lynn

Error -10401 occurred at AI Group Config - in relation to USB-6008

I'm attempting to run a simple vi that uses AI Aquire Waveforms.vi to input voltage data that I have coming in from the USB-6008 DAQ. However, when I try running the program, I receive the error:
Error -10401 occurred at AI Group Config
Possible reason(s):
NI-DAQ LV: The specified device is not a National Instruments product, the driver does not support the device (for example, the driver was released before the device was supported), or the device has not been configured using the Measurement & Automation Explorer.
And I'm not sure how to fix it. In MAX, the device seems to be working properly and everyhting seems to work fine in the test panel, so I'm slightly at a loss. I'm running Labview 7.1, and installed NI-DAQmx 7.5 which came with the USB-6008.

Never mind. I'm new to Labview, and didn't realize that I could not use the traditonal Data Aquisition components with the USB-5008 (I didn't even realize that NI-Daqmx was different).

Can I use more than one USB 6008 in the same program?

I am working on a project that may require up to six USB-6008 modules. Before I purchase more I need to know if I can use all six at a time in the same Lab View program. Can anyone help?
Solved!
Go to Solution.

Hello Nick,
LabVIEW is able to handel that number of DAQ tasks quite easily, however you must remember that USB has a maximum bandwidth. Therefore you would have to ensure that you have enough USB hubs on your PC. Typically there are between two to four USB slots per hub and each of these will have a maximum throughput rate which will divided between all devices attached to that hub. Therefore although you may have four USB DAQ devices attached to four USB ports if they are on the same hub you may notice greatly reduced rates of data transfer. What I would suggest rather than purchasing six or more USB 6008, why not purchase one PCI card which is able to handel many more inputs with a larger bandwidth.
Regards
Andrew George @ NI UK

Will USB-6008 DAQ be able to power and record voltage for UMS T5 tensiometer at the same time?

I would like to use my NI USB-6008 to provide power to my UMS T5 tensiometer (http://www.ums-muc.de/en/products/tensiometer/t5.html) as well as take readings from it, but I don't know if this is possible to do properly. The supply voltage for the instrument can be as low as 5V, which I can easily get from the dedicated +5V channel. I am able to power the instrument and connect it to an analog input on the 6008 and measure a voltage in differential mode. However, while reading the support literature for the instrument, I find the following:
"Potential data acquisition pitfalls: Because the pressure transducer is configured in a Wheatstone full bridge, the input voltage and signal mV output cannot be connected to the same reference (ground). Hence, the signal mV output can only be measured using a differential voltage measurement. Therefore, do not attempt to make a single-ended measurement of the pressure transducer mV output." (http://www.decagon.com/assets/Uploads/MeasuringUMSTensiometerswithnon-UMSControlandDataAcquisitionSystems.pdf)
My understanding is that the 6008 can take a differential measurement if I attach the signal "+" and signal "-" to the positive and negative analog input terminals. However, it seems that all of the Ground ports on the 6008 are grounded to the same reference, which would make my voltage measurement invalid according to the paragraph above. So my real questions is: if I attempt to record the voltage using one of the analog inputs on the 6008 in this way, is the measurement valid? Or do I need to find a separate power supply with a different reference ground to ensure that the measurement is accurate?

The specification sheet for that device is very poor. The manual is not much better. Companies which want to sell scientific equipment should publish decent data sheets or get out of business.
In section 3.4.3 General requirements the device is described as a "non-amplified bridge circuit." This information along with the bridge impedance should be in the specifications because it is essential to applying the device under any circumstances other than the nominal behavior at 10.6 V.
The answer to your question is this:
You can use it with the USB-6008. The 5 V power supply will result in output voltages slightly less than half (5/10.6) the voltages specified under nominal conditions. You can use the differential input mode on the USB-6008. The absolute input voltages will be about 2.5 V with the 5 V supply. That voltage is within the working range of the device. The differences will probably be less than 100 mV. The resolution of the USB-6008 on the +/-1 V range is about 0.5 mV so your pressure resolution will be around 1 % of full scale. The input impedance and termination voltage of the USB-6008 will introduce some errors. These may be on the order of 5-10%. I cannot predict much better without the missing bridge impedance specification. Those errors should be systematic and relatively constant. A calibration of the whole system - sensor and DAQ device together should allow you to compensate for much of that error.
Lynn

How do I get multiple inputs?

Hi. I have Logic Pro 9 installed on my Macbook and on my iMac. I have tried to use a 12 channel mixing desk as the inputs for recording, but it will only ever allow me to select 2 inputs. This is on my Macbook only, I don't have the same problem on my iMac. Previously I have a 2 input device (an Apogee Duet) and used this on both computers. When I connect the mixing desk (Yamaha MG166cx-usb via the firewire to USB connector, it shows up in the preferences and allows me to select it as the input and output device under preferences, audio, devices, core audio option. If I add a new audio track, it will only still show me the option of selecting input 1 or input 2. If I do the same on my iMac, it will show multiple inputs. I have uninstalled my previous audio device, and also uninstalled Logic, moved to trash, downloaded again, but the same symptoms are there.

Yes. Of course I read the manual. It quite clearly shows in Cubase, which I haven't installed and don't use 4 stereo and 8 monoaural tracks. It's on page 11 of the hard copy manual. I have however just set up a blank project and tried recording from different channels on the mixer. (1 and 5). I can record either one individually, but only two channels simulaneously, but no more than two channels it seems. Are you saying this is all I ever will achieve with this desk? Seems a bit pointless almost to sell a desk with multiple channels yet only lets you record two of them with one of it's selling points - a USB connection facility. It's not the reason I bought the desk by the way, I use an Apogee Duet to record at home, I just wanted to be able to set up and record each individual channel during a live performance via the PA and then clean up and mix properly at home. Guess I'm not going to get far on that front

Using USB-6008 software timimg Generate waveform

I am using USB-6008 device. Base on it's User Guide, this device on support software-timed and maximum update rate is 150 Hz.
By place a time delay VI for 1ms, I have a 1.660Hz sine signal. Is this wrong for place a time delay VI for software timing?
I would like to generate a 60 Hz signal by using software-timed VI on USB-6008 device. How should I do?
Thanks a lot.

DephinTW,
The update speed of the USB-6008 is largely dependent on the speed of
you computer as well as anything else on your USB bus. If you are using
an older computer or have other USB devices on the bus, you may not
achieve this rate. In order to output a 60Hz signal, the minimum output
sampling rate is 120Hz. This corresponds to an 8.3 msec. delay between
samples. Instead of using the "Wait" VI, you should try using the "Wait
Until Next ms Multiple" VI. Place this in parallel with your
generation. This will synchronize the output with multiples of the PC
clock, rather than waiting for a fixed amount of time, irrespective of
code and USB overhead.
Hope this helps,
Ryan V.
National Instruments
Ryan Verret
Product Marketing Engineer
Signal Generators
National Instruments

How to connect lvdt and loadcell to usb 6008

please help me iam dont know how to choose a daq card. searched a lt but iam lost.
i want to measure force and displacement simultaneously of a suspension test rig and i wanted to use ni usb6008 because of my project budget.
can i use this daq card to measure these parameters ??
please reply.. thanks in advance.
Solved!
Go to Solution.

Hi touheed,
To be able to determine whether or not using a NI USB-6008 would be suitable for your application it would be useful to get a little more information about the measurements you want to take. If possible would you be able to provide the voltage range you intend to measure with your instruments, and the sampling rate you require?
Also I noticed in the subject line that you're going to be using an LVDT, will you also be generating the voltage for this with the 6008, or will this be done seperately?
To give you some context, the NI USB-6008 does not take truly simultaneous readings at each instant, but will rapdily alternate between channels, giving effectively simultaneous samples. As this device has a sampling rate of 10 Ks/s, and you will be using 2 channels, the effective sampling rate for each input would be 5 Ks/s.
Matt H
Applications Engineer
National Instruments UK

Has anyone any experience with a USB-6008 and reading a thermistor value

Labview 8.0 connected to a USB-6008
I am using 'BC Components' NTC Thermistor. I used the express VI to create a Vex input and entered the A,B,& C values from the datasheet. The thermistor is the 10K version and I placed a 10K resistor in series with it. I wired it as is shown in the connection diagram, and applied 2.5 volts to it.
I get completly the wrong temperature readings out of it! I called the NI help line in the UK and the engineer confirmed that I had done everything correctly but couldn't understand why it didn't work.
Any thoughts?
Steve Lawson

I had a similar problem, had it working at one point then screwed it up.
try this:
Attachments:
Temp Pressure EXpress.vi ‏92 KB

Error -200220 LabView 7.1 USB 6008

I have two PC one with LabView 7.0 another one with LabView 7.1 and NI-DAQmx Base 1.4 installed for USB 6008.
If I run example VI for LabView 7.0 on first PC it works OK, but on second one I get Error -200220 occurred at an unidentified location Possible reason(s):
Device identifier is invalid.
Can someone explain me what to do with this error.
I already tried to update LabView to 7.1.1. and drivers to 7.5 but things are getting even worse with it so I reinstalled all back.
Can somebody give me simple VI example for this device (for examle AI monitoring) and may be you can help me with this error.
Sergey.

Sergey,
If i'm being totally honest, I would ditch DAQmx Base and move to DAQmx 7.5, in the long run this will make things ALOT easier.
From your previous post, I'm guessing you already have 7.5 downloaded or on disc somewhere. Install this driver instead. The following guide may help you out:
http://digital.ni.com/manuals.nsf/websearch/5F6EEBAF2522C98B862570120052F35F
As soon as you run into any problems, let me know by posting here and I will work through them with you.
One other thing I would mention is that you may be experiencing problems that have arisen due to multiple install/uninstalls, and the registry may have been mixed and that's why you are having the trouble.
Let me know how your getting on and we can progress together!

Temperature measurement usb 6008 with Thermocouple

Hi,
I am trying to measure temperature with type k thermocouple on USB 6008. I set max for measuring voltage, and got 0 voltage with noise. It would be appreciated if you can help me to wire up properly.
Cheers,

Hi,
You are doing the right thing by acquiring your thermocouple data as a voltage. From there, you can convert it to temperature data after the acquisition.
There are two configurations that you can use to connect your thermocouple to the USB device: Differential and Reference Single Ended (RSE). If you use differential, then you would connect one wire to the + channel and the other wire to the - channel. For example, to use AI 0, you would make connections to AI0 (+) and AI4 (-). If you use RSE mode, then you would connect one wire to an analog input channel and the other wire to ground. So for AI0, you would connect the + to AI0 and the - to ground.
More information about these connections is available in the USB 6008/6009 User Guide. Also, here are two links about the different types of configurations you can use as well as thermocouple polarity:
Field Wiring and Noise Considerations for Analog Signals
How Can I Determine What Kind of Thermocouple I Have and the Correct Polarity of Signal Connections ...
Regards,
Hal L.

PID - USB 6008

Hi, everyone!
I'm Student. I found some example about PID. Reset Counter and make a PWM on Internet, I don't remember those Links. Now I Use them to control motion of DC motor. I use USB - 6008 of my teacher (I borrowed). When I select time to reset counter 20ms but elapse higher 20ms. The purpose of my project only to study, sorry when I changed those Program. Would you please explain for me and help me solve this project . Thank you.
This my VI and Picture my test.
Attachments:
Test PID.zip ‏71 KB

I'm sorry that I need to disappoint you, but your approach doesn't sound very promising. Low cost USB DAQ devices are the worst choice for closed loop control systems due to the lack of hardware timing for the digital outputs or a counter output. With this approach you will run into multiple problems:
Lack of hardware timed output results in a PWM signal with a high amount of jitter.
Compared to other bus technologies like PCI or PXI, USB adds even more jitter in single point output mode.
Running your control loop under Windows (non-deterministic operating system) adds even more jitter and makes tuning very hard.
This is really a worst case scenario for a control system and you will probably end up with a poor solution. Here and here are some other threads about the same topic.
Kind regards,
Jochen Klier
National Instruments

USB-6008 DIO Lines...

I have a USB-6008 that I'm using to develop an application with. The development language used is C# (.NET 2003 with Measurement Studio 7.0). Right now, I have the device successfully reading from the counter input. Since this program reads rising edges from the counter input, I can get the frequency of the input signal and cause something to happen should the frequency rise above a certain threshold.
I'm trying to use the Digital port (port0) to set line 0 high if a condition has been met. I can do this when I select 'Dev1/port0' - I get Port 0 line 0 to go high or low. The problem is that I want to have control over lines 1, 2, 3, 4, 5, 6 and 7 - I only have access to line 0 right now on either Port 0 or Port 1.
Currently I'm using the following imported functions from the C samples included in the NI-DAQmxBase software:
int result = DAQmxBaseCreateTask("", out dioTaskHandle); // create the DIO task...
result = DAQmxBaseCreateDOChan(dioTaskHandle, "Dev1/port0", "", 1); // create DIO channel...
result = DAQmxBaseWriteDigitalScalarU32(dioTaskHandle, true, 1.0, 0, out reserved); // write a 0 to the channel selected
Just a note about the third line of code - the documentation states that parameter 2 of the 'DAQmxBaseWriteDigitalScalarU32()' function must be set to false. When I use false as the 2nd parameter, I end up getting a return value of -1073807346. I can't find what that error is in any documentation. So, I set this value to true - and it works (I get a return value of 0 meaning success).
In my development cycle, I've tested for ways to get access to a single line (other than line 0), and found that when I create a DO channel with the value "Dev1/port0", port 0 line 0 is active. When I create a DO channel with the value "Dev1/port1", port 1 line 0 is active. If I try to create a DO channel with a value of "Dev1/port2" through "Dev1/port7", I get a return value of -200170 (Physical Channel Does Not Exist). The documentation isn't very clear on the ports and single lines for digital output.
My question is - how can I gain access to ALL of the lines of a particular port?
Thanks,
tsc

I just figured out the lines of the port - of course this will happen once I've posted a question. If others run into the same type of problem, here's how to access each individual line of a selected digital port:
line 0 - 0x01 (binary: 0000 0001)
line 1 - 0x02 (binary: 0000 0010)
line 2 - 0x04 (binary: 0000 0100)
line 3 - 0x08 (binary: 0000 1000)
line 4 - 0x10 (binary: 0001 0000)
line 5 - 0x20 (binary: 0010 0000)
line 6 - 0x40 (binary: 0100 0000)
line 7 - 0x80 (binary: 1000 0000)
all lines off - 0x00 (binary: 0000 0000)
all lines on - 0xff (binary: 1111 1111)
// create a task...
result = DAQmxBaseCreateTask("DigitalPort0 Task", out dioTaskHandle);
// create a channel - I'm using Port 0 in this example)...
result = DAQmxBaseCreateDOChan(dioTaskHandle, "Dev1/port0", "", 1);
// turn off all digital lines to the port selected (I do this when starting up)...
result = DAQmxBaseWriteDigitalScalarU32(dioTaskHandle, true, 1.0, 0x00, out reserved);
// if I want to turn on the first line (P0.0) of port0, then I send 0x01 as the fourth parameter...
result = DAQmxBaseWriteDigitalScalarU32(dioTaskHandle, true, 1.0, 0x01, out reserved);
// if I want to turn on the fifth line (P0.5) of port0, then I send 0x20 as the fourth parameter...
result = DAQmxBaseWriteDigitalScalarU32(dioTaskHandle, true, 1.0, 0x20, out reserved);
I hope this will help someone else out using this device and Measurement Studio for .NET.

Multiple inputs in NI usb 6008

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