DAQ Speed

[MJThurman]

Hi,

I have a project that I am starting that I would appreciate some advice on. I need to develop a solution for interfacing to a third party sensor on a production line. The production line runs at 500 cans/minute and the system I am developing is required to track the cans through different stages of the line. The system I am developing has about 10 digital IOs, 7 Analogue inputs and 1 Quadrature encoder input. I was thinking of using a NI PCI6220 as my DAQ hardware and I was wondering what sort of sampling speed I should expect from it with these number of channels. I need to monitor the inputs continuously and ocassionally toggle outputs. For a first off I was planning to simply loop the system and read these inputs as fast as my PC could, there is no requirement to do complex calculations from the data inputted and there is no logging and only a simple GUI.

Thanks

Matt

[Ton Plomp]

... about 10 digital IOs, 7 Analogue inputs and 1 Quadrature encoder input. I was thinking of using a NI PCI6220

It's not very clear stated in the specs of the M-series card (6xxx-series) but only the first port has the possibility to use a clock as a timing source, for port 1 and up you rely on software timing, which is much slower and not really reliable.

Your card-series of choosing (622x) has 8 inputs on port 0. To get more inputs you need the 625x series which has 24 inputs on port 0.

I am not sure about the quadrature encoder but you should be able to get speed up to the clock-speed of the analogue in for all of the signals (about 1 MHz).

Ton

[Mellroth]

...Your card-series of choosing (622x) has 8 inputs on port 0. To get more inputs you need the 625x series which has 24 inputs on port 0.

I am not sure about the quadrature encoder but you should be able to get speed up to the clock-speed of the analogue in for all of the signals (about 1 MHz).

Ton

I don't think that is entirely true, the PXI-6229 has 32 clocked DIO lines (but all in port 0).

The sample speed of the DIO lines are not possible to define using a internal clock, instead you'll have to use an external timing source (unless you use the default sample clock which I believe is 1MHz for all 622X boards)).

This is usually not that much of a problem, since you can use one of the CLK outputs to generate the sample clock you need, just remember to specify the CLK terminal as the external timing reference in the DIO task.

/J