Suppose that I have a bipolar 10 volt signal, but I am particularly interested in the range around 0. Is it acceptable to tie 2 AIN channels together and set the gain higher on one of the two? The only issue that I see is that the higher gain channel will obviously saturate when the input signal goes out of it's range, but I don't know if this would harm the input.
Thanks,
- Jason
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Yes that it fine, but really no reason to use another channel. You can just grab multiple readings from the same channel using different range settings.
In fact, you could write a little auto-ranging function where you first grab a reading using the 10V range, and then if the reading is <1 you grab another reading using the smallest range that will work. Keep in mind, though, that error is different when you change Range.
AIN are specified to sustain no damage as long as the voltage is less than 20V versus GND, regardless of what Gain/Range setting you are using. Note that voltages of about 13-20 volts will not cause damage but while that voltage is present it can affect readings from other channels.
That makes way more sense than what I was thinking.
Part of the train of thought came from the idea of sampling multiple channels and averaging to reduce noise or get better resolution. Is there any potential benefit to averaging multiple channels (say 4 channels with the same gain), or does the total time taken to measure them all outweigh going to a longer settling time on a single channel? It seems that there would be a trade off after a certain number of channels...
Thanks,
- Jason
Usually using the max ResolutionIndex is the first thing to do to get rid of noise you might have in your signal, but beyond that averaging multiple readings is great.
Again there is no reason to connect the signal to multiple channels and grab readings from all to average. It is better to use one channel and grab multiple readings from one channel. For example, in LJLogM you can put "AIN0" in multiple rows and they will all collect AIN0, or in your own application you can call eReadNames and pass in multiple elements of "AIN0".
Ok that all makes sense too. Thanks again!