Deciding on Hardware

[jonrie1]

Hello all,

I'm new to Hi-speed Data Acquisition and to NI in general. We are looking to build some test equiment which would be have the following devices installed:

• 2 rotary encoders (5 VDC TTL, Chan A, B, Z - 2048 lines with 2 markers per revolution) to measure angular position (0-360 degrees) of 2 rotating shafts
• 2 optical micrometers with +/- 10VDC output for measuring gap between shafts
• 2 load cells for measure load of each side of the upper shaft

The test stand will initially be manually rotated but could eventually be driven at speeds up to 1100 products per min (2 products per revolution). I calculated this to be ~18.7k samples per sec to get every encoder pulse.

My first question what is the best hardware fit for the system I am describing. I used the configuration advisor and came up with the following, but do not know if this is the most efficient way to gather this type of data. As with all projects cost is a concern, but not at the expense of loss of necessary data:

cDAQ-9172 United States 120VAC

NI 9201

NI 9401

NI 9237

cRIO-RJ50 Cable (2m, qty 4)

NI 9934 - 25-pin connector kit with screw terminal connectivity and D-Sub shell

NI LabVIEW FDS + SSP

NI 9901 - Desktop Mounting Kit

My 2nd question is can this system collect the data without a computer or is it required to have a computer present to collect and store.

My 3rd question is can the encoder signals be setup to show a 0-360 automatically or will it only show the encoder pulses

My last question is how easy is it to export the data to Excel, Labview, etc for viewing and manipulation.

Any help you can provide would be greatly appreciated.

Thank you in advance,

Jon

[Kevin_Price]

I'm not sure what criteria caused the config advisor to recommend Compact DAQ products.  They may be a fine choice, but given your description I would have suggested the M-series data acq boards.   NI very likely has a tech/sales rep assigned to your area.   If you contact him/her it'll probably help a lot to talk through your current needs (and future dreams) in an actual conversation.

Further tidbits:

1. It sounds like you're planning a high sampling rate primarily to make sure you "get every encoder pulse."   Many data acq boards have counters on board that take care of that for you.  The counters keep a running count of position changes in hardware, and you can choose to sample that count value at any rate that suits you.

2. You'll need a computer to install LabVIEW and create your data acq program.  Many approaches would also use that computer to collect and store the data, but there are other options.

3. You should measure the encoder signals with counters, in which case you won't see pulses.  It'll be pretty easy to display position as a 0-360 deg angle.

4.  Exporting data is also easy -- I'd advise that you plan to use use a simple universal format such as delimited ASCII.

You might consider asking your local NI rep to refer you to an area company that specializes in custom LabVIEW work.   Since this stuff is all brand new to you, you're extremely likely to save a huge amount of calendar time that way.

-Kevin P.

[hoffiz]

Hi Jonrie1,

The system is a good set up for what you want to do but I will still prefer using an M series if you can avoid doing this remotely.  This system configuration will need a host computer to run, the hardware you should be looking is Distributed I/O if you want to be computer independent.  But still for a project like that I will recommend like Kevin said to get in touch with the Inside Sales Representative login in to Contact NI or the phone number: (888) 280-7645.

I hope it helps