How do I acquire and generate analog signals simultaneously?

[Muralidhar]

Hello everyone,

Firstly, thanks for having such a wonderful forum. My name is Murali and I am a graduate student in USA. I am working on a project realted to making a heart simulator and it requires an application to control a set of linear actuators.

A small description of what I want to do is described below:

I have a NI DAQ card, that has 64 analog input channels and 4 analog output channels. A pressure transducer is connected to one of the input channels, and pressure data is acquired from some flow loop. Three linear actuators are connected to three of the four analog outputs. My objective is to trigger these linear actuators when a particular pressure is reached and get them back to their normal position when the pressure goes beyond a particular point.

I am new to using LABVIEW and would appreciate if someone could help me out with this.

thanks
Murali.

[Marni]

Dear Murali,

If I understand you correctly, you want to trigger 3 analog output lines off of 1 analog input line. There is a KnowledgeBase called How Do I Use a Digital Trigger in LabVIEW to Start and Stop Acquiring Data? that describes how to use a start and reference trigger. You can take this example, change it to do analog triggering, and stick a while loop around the whole thing to make it continuous. Please take a look at it and let me know if you have any questions. Have a great day!

Sincerely,

Marni S.

[Muralidhar]

Dear Marni,

Thanks for your help. But I have a problem with what you suggested. My DAQ card is a M series PCI- 6229 card which does not support analog triggering. I still havent figured out what to do now.

Please let me know if you have any suggestions. Do you think conversion of the pressure signal from A to D is a viable option.

Thanks for the help

Regards
Murali.

[Marni]

Dear Murali,

I can't think of a way to trigger off an analog line at two levels without using analog triggers. It looks like you need another board for this application.

Sincerely,

Marni S.

[eaolson]

Depending on the time scale involved, could you continuously monitor the input voltage and send a software trigger when it reaches your trigger value?  That is, basically roll your own analog trigger within software, rather than in hardware.