There are quite a lot channels.
Does I need to check the channels one by one to see if any signals coming in.
Or there is another correct way to do it.
Explain a bit further. Each time you do a DAQmx Read, there are signals coming in. Do you need to detect if there is a specific signal being read?
If it's possible to have data from all channel, and you really have no idea which one will come in, yes, you've to check it one by one.
If you don't tell anyone the difference between no signal, and signal existed, how can anyone answer your question?
Please try to put more effort on your work.
When there is no signal, the input is just a 0 level voltage.
When signal come, it will be a 50Hz sine wave with several second duration.
I am not sure if the card can do simultaneous data collection. Just wonder any standard mechanism or function block for polling multi-channel with good performance.