Using a NI USB-6008 to read a digital number

[alaio_3]

Hi, I'd like to use the NI USB-6008 to read a 26-bits digital number but don't know how i'd do it, i only find a program to read analog inputs... How can I read the 26-bits number ?

[TimoSchott]

Hi

is the digital number binary ( seriell / parallel) or an analog value?

regards timo

[alaio_3]

it's a 26-bit wiegand standard code (serial)

[Dennis_Knutson]

If you want to read a serial data stream with the USB-6008, your best option is to use the analog input. The digital I/O is software timed. That means that you read whenever you command it to read with your program and that timing is very inaccurate on a pc. With an analog input, you can specify number of samples and a sample rate. As long as the timing of the digital data is not greater than the acquisition rate of the 6008, you should get your bit stream. After the waveform is acquired though, I'm not sure how you will know the start of the data though. Does this "standard" have a defined header followed by data?

What kind of device are you trying to communicate with? I'm not at all familiar with Weigand Standard but a quick Google search turned up some Weigand to RS232 converters and that might be an option for you.

[alecjcook]

I am attempting to use LabVIEW to inject a Weigand format token into an access control product and I was wondering if you had had any luck with getting this to work. I really don't want to spend $350 on a RS232 to Weigand converter, but I think the complexitys of sending a clock and data signal from the analog ports of a NI-USB module may be a little beyone my abillitys, can anyone please help?

[TinoMK]

Hi,

Did anyone succeeded to read the Wiegand data format with LabVIEW?

Thanks,

[alecjcook]

The 6008's data rate is too slow to be able to sucsesfully read Weigand data.

[kdmcmullan]

Just about to try to read it with a PXI-7833R. Watch this space.