I don't know what you mean by activating one of the inputs. Are you doing something in software or is this something you're doing in hardware? With the DAQ Assistant, you cannot activate or deactivate any channels that you have defined. As I said, all channels in the task will always be acquired. There is no way for the DAQ Assistant to know that something has been done externally. If you only want one channel to be measured, don't define multiple channels in the DAQ Assistant. You could create multiple DAQ Assistants and put them in a case structure. Or, as I mentioned before, if you know that only one of the inputs is supposed to be active, make the other indicators invisible.
Also, if you have multiple channels defined in a task but only one channel is physically connected, the open/floating inputs will measure the same as the physically connected channel. This is expected. Again, if you know which channel is connected, you don't have to display the other indicators or you don't have to ue the index array function to get the value. That's what case statements can be used for. But, the DAQ Assistant will still acquire all channels that are defined in the task.
It doesn't sound like there is anything wrong with the hardware or software. It just sounds like you don't quite understand how multiple channel data acquisition is done.
Thanks for the reply again,
I have 15 voltage inputs physically wired to the DAQpad-6015 (ai0 - ai14). On the front panel is an indicator that corresponds to each physical channel. I have set up the DAQpad-6015 with NI_DAQmx, the DAQpad is recognized and passes the self test. All (15) channels have been selected, named, voltage parameters set and the physical connections diagram has been follolwed. On the block diagram through the DAQ assistant - from the data terminal (of the DAQ Assistant) is wired a 'from DDT' converter and from that is wired an index array where all of the indicators from the front panel are wired to the element terminals (of the index array).
My problem is that when I physically apply a test voltage to one of the inputs into the DAQpad-6015 all of the indicators on the front panel respond - that is the whole bunch of them (all 15) move exaclty the same! Rats!
I think I am doing a poor job of describing what I have and am trying to do but this message is closer I think.
Your help is appreciated.
Oh, now I hear you, yes I have all the other inputs to the DAQpad hanging in space, so you are saying that they are 'floatin', therefore will show activity on front panel. I need to connect them all. Sort of like graound them (?). I will do that.