how to acquire signal from a synchronous serial data transmission?

[sly@fmo]

Hi,
I would like to know which kind of hardware I can use to acquire signal from an absolute encoder (position sensor) linked to a control system via a synchronous serial data transmittion without perturbate this transmission.
The idea is to divide the data signal from the encoder and the clock signal from the control system with optical isolators. In order to get the data to another acquisition system who measure the position directly from the encoder without modify the primary control system.
The clock frequency is about 80kHz until 800kHz. the voltage is 0V for the "low" state and 5V for the "high" state... see the attachments for more details about the data transmission.
I'm running
under windows2000 and I'm using labview6.1 for the software development...
I've already got a PCI6602 card. I'm using it to acquire the data from incremental encoders. Can it be set up to acquire this type of signal? if not wich ni card is designad for this application.

Thanks,
Sylvain

[Spencer S.]

Sylvain,

To acquire serial data at this rate, you will want to consider the NI 6533. Below, I have included a link to the product page for this device:

NI PCI-6533 (DIO-32HS)


I have also included a link to a document that discusses performing serial I/O with the NI 6533. It explains the concepts involved and provides links to a number of LabVIEW example programs.

Serial I/O with the NI 653X

Good luck with your application.

Spencer S.