Keithley KUSB-3100, User Manual

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Principles of Operation
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Input Ranges and Gains
The KUSB-3100 module features an input range of ±10 V. Use
software to specify the input range. Note that this is the range for the
entire analog input subsystem, not the range per channel.
The KUSB-3100 module supports programmable gains to allow many
more effective input ranges.
Table 2 lists the supported gains and
effective input ranges for each module.
For each channel on the KUSB-3100 module, choose the gain that has
the smallest effective range that includes the signal you want to
measure. For example, if your analog input signal ranges between
– 2.0 V and +2.0, specify a gain of 4 for the channel; the effective input
range for this channel is then – 2.5 V to +2.5 V, which provides the
best sampling accuracy for that channel.
The way you specify gain depends on how you specified the
channels, as described in the following subsections.
Table 2: Effective Input Range
Gain Bipolar Input Range
1 ±10 V
2 ±5 V
4 ±2.5 V
8 ±1.25 V