Hello Diana and all,
Generally, for accelerometer measurements, we recommend a Dynamic Signal Analyzer (DSA) device for higher resolution measurements. Depending on your measurement requirements (accuracy, resolution, measurement time, etc) you may be able to use a multifunction data acquisition (DAQ) solution like the one graziano mentioned. A few questions you may need to consider in finding the best device would include:
1. What type of measurement are you taking? You mentioned an accelerometer, would these be Integrated Electronic Piezoelectric (IEPE) accelerometers?
2. Through what range of voltages are you expecting to measure? This is important when selecting the device and any signal conditioning options you may need.
3. What accuracy and resolution are you looking for in your measurements?
4. What development environment are you considering? Most of my comments will be directed towards a LabVIEW based solution, but the same concepts could apply to text based environments like C or .NET.
5. Do you want to perform any data processing in your software or purely datalogging?
For the highest resolution and best accuracy, you may want to consider a DSA based solution. Based on the details you provided (100 kS/sec & 16 channels) I would recommend the NI PCI-4472, which you can find online here. This is an 8-channel DSA device which can sample up to 102.4 kS/sec per channel. Since there are only 8 channels, you would probably need to get two devices and then synchronize your devices by sharing signals across the real-time system integration (RTSI) bus. Using RTSI bus cables like these, you can share timing and synchronization signals between multiple devices.
I recommended the NI PCI-4472 based on the fact that most computers offer PCI slots, so it would be the easiest to use with equipment you likely already have. If you are willing to consider a PXI based solution, you could eliminate the need for synchronization by using the NI PXI-4496, which has 16 channels. However, a PXI solution would require a chassis and controller which would add some additional cost. For more information on PXI, I would recommend you examine this application note and visit the PXI Advisor.
If you are willing to sacrifice some accuracy and resolution for a more cost effective solution, you could consider a DAQ based implementation. In this case, you would probably use one of our S Series simultaneous sampling devices (like the PCI-6143 recommended by garziano) to acquire your data. Comparing the S Series with the DSA, you can see that the DSA has 24 bits of resolution with a 110 dB dynamic range through +/- 10 V while the S Series DAQ device only has 16 bits of resolution and a +/- 5 V signal range. Additionally, the DSA device has built in IEPE conditioning for accelerometers.
So far, I have discussed the hardware for acquiring your data, but I would like to point out that neither the DSA devices nor the S Series devices can trigger off multiple channels. Each of them can only perform hardware triggering on a single channel. However, it would be fairly easy to implement a software algorithm that compared the data from the channels with your trigger level and then only logged the data when your trigger conditions were met. By continuously acquiring data and using software to decide when to log, you can also meet your pre-trigger conditions by keeping a certain number of samples in a buffer and then logging the buffer and current data when the trigger occurs. Hope this information helps, let us know if you have any other questions.
Matt Anderson
Hardware Services Marketing Manager
National Instruments
