Tachometer sensor for NI9233

[Ivan99]

Anybody knows where to get a tachometer sensor which is complying to NI9233?

[Wilfried_71]

Hello,

I'm not sure that you can plug a simple analog input voltage in this module. It's just made for IEPE sensor (accelerometer and microphone), with special supply and acquisition card. I think you need the 9215 or 9205 analog input module to connect this kind of sensor.

[Neal M]

Hello Ivan99,

Wilfried is correct, the NI 9233 is one of our Dynamic Signal Acquisition modules.  The inputs provide an IEPE excitation to devices such as accelerometers and microphones.  My experience with tachometers is that they are a passive device (do not need excitation).  Unless you can find one that can take 2mA of excitation, then you will have issues with your acquisition using the NI 9233.

The module that you want to use with a tachometer depends on how you want the signal to be read.  I believe that most tachometers output a digital signal (e.g. a specific number of pulses per revolution, the frequency would tell you the rpm), so any of our modules that have a digital input (such as the NI 9422) would work.

I have also heard of tachometers that provide an analog signal (X Volts = Y RPM).  If this is the case, then you could use any of our modules that have an analog input (such as the NI 9201) with the range capacity of your tachometer.

I would recommend calling one of our Technical Representatives (www.ni.com/contact).  They are very good at helping you spec things such as sensors.

I hope this gives you a better idea of where to look.

[JaredA]

Try giving PCB or Banner Engineering a call. I don't remember the exact model numbers, but I believe they both make a laser tach which work with an IEPE input.

[Ivan99]

Thanks all for information.

I would prefer to purchase the following Monarch Instrument optical sensor ROS-P for my NI9233. However, according to NI9233 spec., its excitation current is limited to minimum 2mA and typical 2.2mA however the optical sensor requires 45mA to work. May I know what is the maximum current for NI9233 module? I would prefer a self powered sensor which not is requiring any interface module as it is not flexible especially during oversea business trip with the equipment (adding weight and consume luggage space).  

Meanwhile, I also have a NI9411 module with input current ±1 mA at 5V, and internally limited ±4 mA input current for I/O protection. May I know what is the maximum current for this NI9411 module?Perhaps I have to source for the other type of sensor which can work within 2-3mA to work with either NI9233 or NI9411.

Attached is the different type of sensor spec. I got from Monarch Instrument. Please advise which type of sensor is suitable (I need analog input for my measurement). Thank you.

[Neal M]

Hello again Ivan99,

From looking at the specifications for the Monarch ROS tachometer,  I believe there may be some confustion as how the 9233 provides excitation.  The 9233 provides IEPE excitation which means that a constant current is applied to 2 wires and then the voltage is measured across these same wires.  This is the type of excitation used for microphones and accelerometers.  The specification of the 9233 you refer to means that the device provides a nominal 2.2mA current constantly, but that current will not drop below 2mA.  The IEPE is not configurable, so it always will be this 2mA.

The excitation that your tachometer appears to need is external excitation.  This is when a voltage/current is applied on separate wires from the measurement. This type of excitation is good for powering devices or wheatstone bridges.

This difference may or may not disqualify the tachometer you are looking at.   If the circuitry is such that you could compensate somehow for the added current without damaging or changing the behaivior of the device, then you could still use the 9233. If however, there is additional circuitry involved (which there probably is), then this may not work.  I would recommmend contacting Monarch to find out.

The 9411 can provide the necessary excitation voltage/current, however it needs to be powered by an external source (as seen in the operating instructions).  The reason this is there (instead of using the external source directly) is to make wiring devices easier:



You may want to consider using this device instead of the 9233 for your input.  It appears that you could use logic levels to input on the digital lines of the 9411 and then an external power supply for the excitation.

I hope this clears things up and gives you some ideas.

Message Edited by Neal M on 12-05-2007 11:46 AM

Message Edited by Neal M on 12-05-2007 11:47 AM

[Vinnygalbo]

I too believe that banner engineering should have a tachometer sensor that meets your criteria.

http://www.clrwtr.com/Banner-Engineering-Sensors.htm

You may want to give sunx/panasonic a try too. They have been adding new sensors to their product line lately.

http://www.clrwtr.com/SUNX.htm

[Vinnygalbo]

I too believe that banner engineering should have a tachometer sensor that meets your criteria.

http://www.clrwtr.com/Banner-Engineering-Sensors.htm

You may want to give sunx/panasonic a try too. They have been adding new sensors to their product line lately.

http://www.clrwtr.com/SUNX.htm