Looking at your code, I think I know what you want to do, but it is sometimes a good idea to "write it down" (Document First) and explain it to us. Here's what I think:
- You have a Delimited Spreadsheet that has Time, two Analog Signals, and a Digital Signal that should represent 10 seconds of Analog and Digital Data.
- You want to read this Profile, then "play" it into two Analog Output Channels and a Digital Output Channel, while simultaneously sampling from an unspecified number of Analog Input Channels.
- It is not clear if you intend a fixed order to these two steps (though it seems "logical" to read the Spreadsheet before playing its Profile and collecting data).
- While collecting data (which should take 10 seconds), there does not seem to be any simultaneous output, only a Chart display after all the data are collected.
If you code an Event Loop to handle the "Load Profile" and "Run Profile" buttons, they could serve as a "Producer" (of Messages) for the Message Handler loop (acting as a Consumer). To force the user to push Load Profile before Run Profile, start with Run Profile not visible. Make both Buttons the Rectangular buttons (like Stop) that are Latch when Released (any Boolean button can be set this way, but by a convention spanning at least a decade, square ones latch and round/oval ones are Switch when Pressed).
The Message Handler should have several Messages to which it responds.
- Initialize DAQ (which could be automatically sent in when the program starts) sets up the three DAQ devices and saves their Task lines in Shift Registers.
- Load Profile might have several sub-Messages, particularly if you want to query the User for the Profile to use. It should Load the Profile and do any displays, make the "Run Profile" button visible, and save all relevant parameters in Shift Registers in the MH Loop.
- Run Profile should run the Profile. You may want have additional Message cases to separate starting the Profile (starting the Clock and the DAQ devices), collecting data (you currently have a While loop, but it looks like the DAQ devices should be able to do all the timing for you "at once", no need for checking "am I done?", and possibly a final Message to process/display/compute timing for the Run)
Use the Event Loop to send the Message Handler the Load Profile and Run Profile Messages when you press their buttons. You should also have it process the Stop button and send an Exit (or Stop) Message to stop the Message Handler (and it should also stop the Event Loop).
Note that this scheme gets rid of all Local Variables and also removes the need for any need for Value Property nodes for variables, substituting Wires in Shift Registers to hold "Variables", and using the Controls to initialize them.
While you are at it, you don't need any Sequence Frames in this routine. You are doing most of the sequencing using the Error Line (good!), and can do more using the Message Handler's "Message" states and Shift Registers. Let Data Flow work for you.
Since you are using DAQmx, and your DAQ devices (typically) have much better clocks than your Windows PC, you should not need any timing functions in this code (except, if you want, a timer to verify that playing a 10-second Analog Signal to an Analog Output device at the same sampling rate used to acquire it does, indeed, take 10 seconds).
Don't be afraid to "hide messy details" in a sub-VI (for which you create a VI Icon, using the Icon Editor, possibly a Square with White interior on which you write 2-3 short words that say what the VI does). I'll admit your code is simple enough that you might not need such encapsulation (yet).
Bob Schor
