digital tachometer with NI USB 6008

[444444]

I want to use USB-6008 DAQ to input voltage sensor,current sensor,techogenerator input and relay output and dynamic braking output.

[444444]

i am doing my project for the control of induction motor i have to measure following parameters .these parameters are taken from tachometer ,overvoltage sensor ,over current sensor ,these three parameter are in analog form.i want to give these three input  to a Ni daq to intrface with lab view and also want to take two output contorl signal from labview through Ni daq .now my question is whitch daq  i use which filfull  all my these requirement

[GarPar]

Hi 444444 -

     From the sound of your application, the USB 6008 will not work.  Tachometers are usually digital outputs (some are analog).  If your tachometer is a digital output, you can't use the 6008 because it has no digital timebase.  Additionally, your relay output probably requires digital timing, in which case the 6008 won't work.  For the over-current sensor, you can use an analog voltage input.  You would just place a resistor in series with your input signal.  Then, V=IR -----> I = V/R.

     You might look into getting a USB 6221, which has hardware digital timing capabilities.

     I hope this helps!

Regards,

[fadz_pinky]

Hi,

From the previous discussion, stated that NI USB 6008 can't work with digital output tachometer. Is it all type of digital output tachometer can't work with this USB DAQ because of the limitation itself? correct me if I'm wrong.

Thank You,

Regards,

Fadz

[fadz_pinky]

Hi,

From the previous discussion, stated that NI USB 6008 can't work with digital output tachometer. Is it all type of digital output tachometer can't work with this USB DAQ because of the limitation itself? correct me if I'm wrong.

Thank You,

Regards,

Fadz

[johnsold]

The USB-6008 has only software-timed digital input and output. It cannot respond fast enough to be certain that you capture every tachometer output pulse and it will have large uncertainties in the timing of the pulses it does capture. Thus, it is not capable of measuring the speed through a digital input.

In one of your posts you state that the tachometer has an analog output.

It may be possible to use the USB-6008 with an analog tachometer, depending on the frequency range of its output. Since you are using three analog input channels, the fastest you can sample is 3333 Hz.  If your tachometer maximum output frequency is less than 1600 Hz, then you should be able to measure it with an analog input. Use Extract Tone Information.vi to get the frequency after you acquire the data.

Lynn

[cody_a]

I would also keep in mind that any DAQ device with a USB bus (such as the 6008) is typically not well suited for closed loop control applications (such as motor control).  Since the USB bus does not support hardware-timed single point acquisition and generation modes, your input task will always need to acquire a waveform of data for each channel (which you then must decimate, average, etc, to get to a single point for your control algorithm) and generate either a waveform of data (probably not suitable) or generate a single data point that is software-timed, and therefore has high jitter.

My recommendation would be a PCIe-based device, such as the PCIe-6320, if single-point acquisition and low jitter are important to your application.

[fadz_pinky]

Thank for the above information. Actually I am trying to use Hall sensor Hall switch Tachometer ​​Speed Counter Module (as attach below) with NI 6008 but still think about the compatibility for both device to work together. Can you help me on this. Is it compatible for NI 6008 to use with this type of tachometer for motor speed application?

Thank You

Module features: 

1.can use 3-5.5v DC power supply 

2.the output signal of the Hall real 

3.through more stable after finishing the comparator output signal 

4.the comparator output capability 16mA 

5.a power indicator light 

6.the comparator output indicator lamp 

Module Interface Description: 

1.DO1-- 1 TTL level output 
2.DO2-- 2-way TTL-level output 
3.DO3-- 3-way TTL-level output 
4.DO4-- 4-way TTL-level output 
5.GND-- connected to the supply negative 
6.VCC-- positive power supply 

[ShamWOW!!]

Hello, 

If you are using a TTL signal, then you should be able to comfortably use the counter on the device in order to measure the speed of your motor. 

Best,

Shamik C 

Applications Engineer 

National Instruments 

[johnsold]

Please post the manufacturer and model of your tachometer or a link to its data sheet. We are doing a lot of guessing about what is actually required.

Lynn