Passing a 8 bit information into laptop through BNC2120

[Wai-shun]

For a project I am working on now. I am using an incremental optical encoder to detect and measure linear displacement. With the encoders I bought some interface chip which goes with it and it has a 8 bit counter in it and has 8 connetion pins corresponding to the 8 bits. the counter will count up and down depending on the displacement.

I wanted to pass this 8 bit into my PC, to LabView, to compute the real-time displacement, vel and accel etc.
I have a BNC 2120 module to work with my laptop. I understand that there are 8 digital I/O ports on it. Is it possible to directly connect the 8pins to the 8 ports and configure it so that it will acquire the binary information and process it? The binary information
on the 8 pins is changing at a rate of no greater than 15-20KHz.
Or is there a simpler way to achieve this?

Many Thanks
your help is very much appreciated
Wilson

[rgharrison]

Hi Wilson,

I assume that you also have a data acquisition board in your computer with a cable to connect to the BNC-2120. The BNC-2120 is essentially a connector box for a data acquisition card. Most NI data acquisition (DAQ) cards have the same 68 pin configuration so that the mapping of the 8 digital I/Os on the DAQ card correspond with the 8 spring(or screw) terminals on the BNC-2120.

BNC-2120 CONNECTOR ACCESSORY FOR E SERIES DAQ DEVICES
http://www.ni.com/pdf/manuals/322444a.pdf

Now, it is important to note that most DAQ boards have static digital I/O. This means you must read the digital value in software. This limits the speed with which you can read digital values to the performance of your O/S and computer system (usually only 1kHz-10kHz).


If you will need hardware timed digital I/O, you might need to upgrade your DAQ card to a high-speed digital I/O card (NI PCI-6533) or a simultaneous sampling multifunction I/O board (NI PCI-6115/6120) which has timed digital I/O (correlated digital).

Anyway, hope that helps. Have a good day.

Ron