When acquiring data from one analog input channel with my KUSB module the data looks good, however, when acquiring more than one channel the data looks corrupt, especially when using a high gain. Why is this occurring?
USB Modules: KUSB-3100 Series: KUSB-3102, KUSB-3108, KUSB-3116,
Question:I get good readings when acquiring from one channel using either the KUSB-3102, KUSB-3108, or KUSB-3116. However, when acquiring more than one channel the data is corrupt, especially when using a high gain. Why is this occurring?
Answer:These modules have high impedance inputs (100M ohm).If your signals are coming from a high impedance source, they will not have time to settle out when doing a channel scan.The settling time increases when a high gain is applied.As a remedy, use instrumentation amplifiers between the inputs and our module. Analog Devices part #AD623 is a proven resolution.
Copyright 2003, Keithley Instruments, Inc.
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