Data Translation DT9812 Series, User Manual

Page: 60 / 124

Chapter 5
60
Using software, specify the channels in the order you want to sample them. You can enter up
to 32 entries in the channel list. The channels are read in order from the first entry in the list to
the last entry in the list. Refer to
page 62 for more information about the supported conversion
modes.
Input Ranges and Gains
The DT9812-2.5V features an input range of 0 to 2.44 V, while the DT9812-10V,
DT9812-10V-OEM, DT9812A, DT9813-10V, DT9813A, DT9814-10V, and DT9814A modules
feature 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 modules support programmable gains to allow many more effective input ranges. Table 7
lists the supported gains and effective input ranges for each module.
For each channel on the module, choose the gain that has the smallest effective range that
includes the signal you want to measure. For example, if you are using a DT9812-2.5V module
and the range of your analog input signal is 0 to 1.05 V, specify a range of 0 to 2.44 V for the
module and use a gain of 2 for the channel; the effective input range for this channel is then 0
to 1.22 V, which provides the best sampling accuracy for that channel.
You can specify the gain in a single-value operation, or specify the gain for each entry in the
channel list.
Table 7: Effective Input Range
Module Gain
Unipolar
Input Range
Bipolar
Input Range
DT9812-2.5V 1 0 to 2.44 V –
2 0 to 1.22 V –
4 0 to 0.610 V –
8 0 to 0.305 V –
16 0 to 0.1525 V –
DT9812-10V
DT9812-10V-OEM
DT9812A
DT9813-10V
DT9813A
DT9814-10V
DT9814A 1 – ±10 V
2 – ±5 V
4 – ±2.5 V
8 – ±1.25 V