Is it possible to have multiple acquisitions running simultaneously?

[Andy5]

I would like to have 2 acquisitions running simultaneously (As in 2 'AI Starts' both running continuous acquisitions). The acquisitions will run different sample rates.

I don't want to oversample and then downsample later. I will be acquiring from SCXI-1122 modules which multiplex using relays. The relays can't switch quickly.

[Michael_S.]

You cannot run the 1122 at two different sample rates on two different channels, because of the SCXI-1122 hardware and the DAQ card you have to control the SCXI-1122. So the only option is in fact to oversample and pick the needed samples after acquiring the data.

[Andy5]

Michael, I appreciate the response but you do not understand my problem. I would like to sample several 1122 channels. Because of the relays in the 1122 I can't switch quickly from channel to channel. Once I get latched to a channel I can sample very fast; its the latching and settling time that takes forever. If I get data from all 16 channels on the 1122 it takes about 16 seconds. This is fine for my application because I am monitoring thermocouples with the 1122 and the temperatures aren’t changing quickly.

I would also like to sample some “more transient” channels simultaneously on a SCXI-1121 module in the same chassis as the 1122. If I am limited to a single acquisition (as opposed to multiple simultaneous acquisitions), th
en I have to wait 16 seconds for the 1122 to get done before I can acquire from the 1121.

What I would like to have is a dedicated acquisition continuously scrolling though my thermocouple channels (updating temperatures every 16 seconds), and a second acquisition continuously scrolling through my 1121 channels and updating indicators every 0.5 second.

[Michael_S.]

Andy,

To do this you will need to have two DAQ cards, one can be put in parallel mode and can read only the 1121 but at the rate you need. Then the other DAQ card can control the 1122 and run it at whatever rate it can go.

[5ubtle]

Thanks Michael. I have 2 PCMCIA DAQ cards. I'll give it a try.

Andy.

"Michael S." wrote in message
news:506500000005000000AC500000-1005954886000@exchange.ni.com...
> Andy,
>
> To do this you will need to have two DAQ cards, one can be put in
> parallel mode and can read only the 1121 but at the rate you need.
> Then the other DAQ card can control the 1122 and run it at whatever
> rate it can go.