What you need to do is a continuous scan. The AI Read will have to be in a while loop that runs 3 times (for A > .3, b > .3, and C > . 3) On the conditional retrieval input of the AI Read VI, you'll need to check what the iteration of the loop is, and set the conditions of the read for the appropriate channel. This will read the buffer, and return the buffer if the trigger condition exists. If the trigger condition exists, exit the while loop (because you have data now). On any AI Reads following the trigger condition, if you want to continuously read the data, you'll have the AI Read with no conditional retrieval.
Next, you'll have to specify to the AI Read VI WHERE to get the data from the buffer. This is key, because if you don't, it will move the read marker in the buffer, and on the next iteration, it won't be scanning the same data for a different trigger condition.
Therefore, you'll need to wire a read position to the AI Read. check out the attached VI, and I think you'll get the idea.