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i240 and i4xx MAXIMUM SAMPLE RATES
REFERENCE > ADVANCED TECHNIQUES >

The following table shows maximum aggregate sample rates for an i240 USB controller attached to an i4xx Card Cage. To calculate the sample rate for each channel, divide by the number of channels attached to the i240 controller. For example, if the maximum aggregate sample rate is 166Ksamples/sec/controller, and you digitize 4 channels, then you could digitize each channel at 41Ks/sec/channel. Or, digitize two channels at 88K each.

One can attach up to eight i240/i60x controllers to a computer to increase total system throughput. For example, four i240 controllers (where each is attached to a separate i4xx Card Cage or i100 box) can digitize 16 total channels at 41Ks/sec/channel; or 32 channels at 20.5K each. In this example, each controller runs at 166Ks/sec/controller and the entire system runs at 664Ks/sec/system. For more details on working with multiple controllers, click here.

The last column of the below table refers to low level signals (≤ ±80mV range). These are common when working with sensors such as a strain gage, load cell or thermocouple. Notice that the only way to digitize fast (e.g. ≥ 2K s/sec/controller) with a low level signal is to digitize directly into an i423 card (to get ≤ 68K s/sec/controller).

 Max Aggregate Sample Rate per Controller (K samples/second/controller) Model ±10V range ±5V range ±1.2V range ±10mV..±80mV range i430 166 166 129 1.4 i420 94 90 83 1.4 i423 113 98 68 i100 166 133 1

Assumptions

• The ±1.2V range... ±10V columns assumes you are digitizing between 1 and 8 channels per i2x0 controller.
• When digitizing from an i42x card (e.g. i420, i423), it is assumed that an i430 A/D card is installed in the i4xx Card Cage; since the i42x does not include an A/D.
• Setup: instruNet World v3.0.37, i240 controller attached to i4xx Card Cage, Strip Chart, 100000 samples/scan, 1000 scans, AUTO hScale (1sec/div), 1 meter Db25 Cable (4000Mbps), Dell 8600 Laptop (manufactured 2006)
• Things that will decrease sample rate: longer Db25 cable, slower computer, optical-isolator, digital filtering, plotting, display size, number of card cages, number of channels, number of controllers.