Can anybody give me a clear explanation on Sampling rate and Scan rate as I am bit confused on the same?

[India]

I am confused on the Sampling rate & Scan rate parameters. Because one is represented in samples & other in time.

Please anybody can give me an clear explaniation of the same with an example illustrating the same. I want to understand very clearly the same as both are very inter-related to each other.

Also kindly attach any further notes to be read on the same.

[Nim]

Sampling rate will have an effect on the time between measuring two consecutive channels (inter-channel delay). Scan rate determines the time between when a particular channel is sampled again. eg using a 200kS/s board with a a scan list consisting of 2 channels, the scan rate could be 100k scans per second and the sampling rate would be 200k samples per second - this would be the max for a 200kS/s board.

[Cool guy]

When you configure a data acquisition process using interval sampling, you specify a list of one or more channels from which to acquire data. This list is called a scan list. One scan consists of one reading (or sample) from each of the requested channels in the scan list. The scan rate tells us how often a new scan is initiated. The scan rate is regulated by the scan clock. The source of the scan clock may be regulated by an internal timer on the data acquisition (DAQ) board or by an external clock signal. Note: Some non-plug and play (legacy) DAQ boards do not have a scan clock. They only have a channel clock. These boards use round-robin sampling (see the related link below).The interchannel delay is how much time passes between sampling consecutive channels in the scan list. The interchannel delay must be short enough to allow sampling of all the channels in the channel list, within one scan period. The greater the interchannel delay, the more time your amplifier is allowed to settle before the next channel reading (see the related links below).The channel rate is the reciprocal of the interchannel delay. By default, the channel rate is calculated automatically by the NI-DAQ driver software. You can also specify the channel rate explicitly by setting the channel clock to be based on an internal timer on the data acquisition board or an external clock signal. In LabVIEW, you can set the internal channel clock rate using the Interchannel Delay parameter in AI Config.vi (see the related link below). Note: Our simultaneous sampling boards have only a scan clock. Since these boards are not multiplexed, they have no need for a channel clock.The term sampling rate is more general and may be used to describe the per channel acquisition rate or the aggregate acquisition rate. This is the specification given to our data acquisition boards. For example, the PCI-MIO-16E-1 is capable of a 1.25 MS/s aggregate sampling rate. This may consist of 1.25 MS/s on one channel or 250 kS/s on five channels. Thus the per channel rate depends on the number of channels scanned for boards with both a scan clock and a channel clock.