Sure, a low pass filter is always the best bet. I was trying to offer you something you could use with the hardware that you had, without adding anything additional.
I'm not quite sure I understand what you mean by synchronizing the chart speed with the acquisition. By definition, when you wire the output of your acquisition to the chart on your front panel, it is updated right then.
So, to reiterate this point, I'll describe what the inputs you asked about do, as well as what actual values would do.
The scan rate is how fast you would like your DAQ board to scan your data. Let's say I'm reading a temperature, so this doesn't need to happen fast. Therefore, I'll set it to 1, or 1 scan per second.
Next, the "no. of scans to read at a time" is how much data the VI should read from the buffer on every iteration. Keep in mind this data has to be available when the call is made, or the VI waits until it is ready. Therefore, if I wanted 5 scans (in this case would be 5 seconds of data, because of the 1 scan per second scan rate), I'd put in 5, but the data wouldn't appear for 5 seconds.
The buffer size is how much memory you want to set aside for the acquisition. This will depend on your scan rate and the number of scans you want to read at a time. In my example, if I was sampling at 1 scan per second and reading 5 samples per loop, that means my buffer would have to be a minimum of 5 scans, or just 5. Typically I take the number of scans to read at a time and multiply it by 2, and that's the MINIMUM buffer size I'd use. That allows for delays in your loop due to Windows. If the buffer isn't big enough, then you get overwrite errors, where the DAQ board is trying to write data into the buffer over data that you haven't read from the buffer yet, so data will be lost.
Lastly, a comment about a strip chart. You can update a strip chart one data point at a time, or as my example above, multiple points at a time. Where multiple points at a time would be most advantageous is when you have a signal you'd like to sample faster than, say, 10 samples per second. Since it takes time to update a graph or chart, you'd like to update it at one time, and if it isn't a problem, I'd just read 10 scans, or 1 second, of data and update the graph once a second with 10 data points. Got it?
So, in a nutshell, your chart "update speed" would be the number of scans to read at a time divided by the scan rate. That would be the number of times per second your chart would update.
Mark
