LabVIEW
ADC conversion attempted before the prior conversion was complete.
If the samples to read that you're talking about is the value connected to the top of DAQmx Timing, then no - this controls the buffer size when you wire the "Continuous Samples" option. The Detailed Help (available via right-click > Help or via Context Help then "Detailed help" at the bottom (use Ctrl-H to open/close context help)) can give you some additional text describing the inputs to the Timing function.
If you mean the samples to read connected to DAQmx Read, then that is the number of samples that will be output by the function (assuming no timeout). In that case, the node will take ~5s to finish, because it tries to read 5 samples and only gets 1/s.
What did you change that caused the error to begin appearing (I know that if you knew the answer to this exactly, you'd have no problem fixing it, but it's worth thinking about and trying to describe - maybe we can take a guess based on your description).
I took a look at the NI 9219 Datasheet and it tells me that the module has 4 timing modes: High Resolution, Best {50,60} Hz rejection and High Speed.
I'm guessing that you're using the High Resolution mode - if so, can you try with perhaps one of the "Best ... Hz" modes (probably choose whichever frequency is the power line in your country/building 🙂 ) to see if that will help?
It certainly looks like the High Res mode should be fine at 1Hz, but confirming that it's a timing problem in the module would be a good start, I guess. Assuming that the problem disappears with a different mode, we can try and work out why it's having a problem with 1S/s/ch (how many channels are you using, by the way?) in High Res.
If you can upload the VI you're using to make the measurements, that might also be helpful. Failing that, the block diagram as an image or snippet (preference for the snippet!) would be a reasonable second place.
