Triggered acquisition start w/ ChicoPlus & SD module

[msvilans]

Hi,

Some National Instruments data acquisition devices have the capability to trigger data acquisition from an external digital trigger.

I'm wondering if a similar capability exists in ChicoPlus with an SD module?

I would like to acquire data at 36000Hz, but the acquisition should only start when an external trigger line goes to high. In other words, after I call Caliente.Start(), nothing should happen until the trigger goes high.

Thanks very much,
Markus.

[gmiller]

There are several possible ways to do this.
First you have to remember that the SD does take warm up time, so an instant start on some outside gate is not recommended, the first 1/2second of data will not be very accurate.

It is possible to use the ChicoPlus built in gates for Timer 0, 1. If you use a multi clock you can even set these timers to work together for a finner resolution. The DIO port has the gate and if you wanted an input for clock source.

Another method would be to add the DIO port to your stream and watch the DIO output for a change in the pin number hooked up. This will give you the exact data point in the buffer or you can just start logging from the beginning of the recognized buffer. The A/D will be up to speed and all points will be valid. In the search of the DIO data this will depend on how long your gate is on. If it is a long pulse then only looking at the last data point in a buffer is necessary. If it is relativity short then you may have to search each point in the buffer to find it.

Gary

[msvilans]

Hi Gary,

Thanks for the idea on adding a DIO channel. I think this will be the most convenient solution. It will be easy to look for the positive edge on the DIO bit.

Thanks,
Markus.