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About ISO-Channel Technology
Figure 45: When measuring two input signals with channel-to-channel isolation, three ground
references are provided (signal 0, signal 1, and PC ground).
New Application Derived from Isolated Channels
A typical application of measuring 48 channels of varying voltages from sensors, such as
batteries, thermocouples, RTDs pressure sensors, etc., often must use different instruments
because of the various ranges needed. Standard ranges of ±10 V may handle some
applications, but not others, to the required resolution and accuracy.
With isolation per channel, combinations of channels can be used to measure higher voltage
ranges.
Figure 46
shows a configuration of 2 separate channels "ganged up" to measure a
signal of up to 20 V. Normally each input would measure ±10 V. But, by using two identical
channels, a range of twice that level can be accommodated. The output readings of each A/D
are then summed to give the very accurate result. This is possible because the isolation
between channels allows the return of the first channel to "float up" to a level halfway
between the input signal. This reflects the accurate impedance balance of each input, and the
high common mode rejection of each stage.
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