Use NI MAX to configure a task for the three transducers. That way you can play with teh # samples and sample rate independent of the vi. You can do a singe task or three independent task depending on how critical your accuracy is as you will create a scale in MAX to convert the value of the electrical signal to your desired units. If this is a general app and a single conversion will work for all three then you can use the same scale and a single task.
When you do a read with a single task, you will get an array and you can keep it arrayed or split it out per transducer and then easiest to do a mean function to get an average of the samples.
You can set up to write any way you want, to a single file or multiple files. Best way depends on what you are trying to accomplish and what you want to do with the data once it is written.
Doug
"My only wish is that I am capable of learning each and every day until my last breath."
