Data Translation DT9834 Series, User Manual

Page: 83 / 186

Principles of Operation
83
Input Ranges and Gains
Table 9 lists the supported gains and effective bipolar input ranges for each.
Using software, specify a range of
−
10 V to +10 V. Note that this is the range for the entire
analog input subsystem, not the range per channel.
For each channel, choose the gain that has the smallest effective range that includes the signal
you want to measure. For example, if the range of your analog input signal is ±1.05 V, specify
a range of
−
10 V to +10 V for the module and use a gain of 8 for the channel; the effective input
range for this channel is then ±1.25 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.
The simplest way to specify gain for a single channel is to specify the gain for a single-value
analog input operation using software; refer to
page 84 for more information on single-value
operations.
If you are using an analog input channel list, you can use software to specify the gain for each
analog input channel entry in the analog input channel list.
Note: For channel 16 or 32 (the digital input port) and channels 17 through 26 or channels 33
through 42 (the counter/timer channels), specify a gain of 1.
Table 9: Effective Input Range
Gain Input Range
1 ±10 V
2 ±5 V
4 ±2.5 V
8 ±1.25 V