Data Translation DT3000 Series, Руководство пользователя, Страница: 71 / 156

Chapter 6
70
Note: For pseudo-differential inputs, specify single-ended in software; in this case, how you
wire these signals determines the configuration.
All input channels have high impedance. Each incorporates ±35 V over-voltage protection
when the board is on and ±20 V over-voltage protection when the board is off.
DT3000 Series boards can acquire data from a single analog input channel or from a group of
analog input channels. Depending on the number of channels supported by the board,
channels are numbered 0 to 15, 0 to 31, or 0 to 63 for single-ended and pseudo-differential
inputs and 0 to 7, 0 to 15, or 0 to 31 for differential inputs. The following subsections describe
how to specify the channels.
Specifying a Single Channel
The simplest way to acquire data from a single channel is to specify the channel for a
single-value analog input operation using software; refer to
page 73 for more information on
single-value operations.
You can also specify a single channel using the analog input channel list, described in the next
section.
Specifying One or More Channels
DT3000 Series boards can read data from one or more analog input channels using an analog
input channel list. You can group the channels in the list sequentially (either starting with 0 or
with any other analog input channel) or randomly. You can also specify a channel more than
once in the list.
Using software, specify the channels in the order you want to sample them. The analog input
channel list corresponds to the Channel-Gain List (CGL) on the board. You can enter up to 512
entries in the list. The channels are read in order (using continuously paced scan mode or
triggered scan mode) from the first entry to the last entry in the channel list. The board reads
the entries in the channel list once per trigger using triggered scan mode. Refer to
page 73 for
more information on the supported conversion modes.
Input Ranges and Gains
Each channel on the DT3000 Series board can measure bipolar analog input signals between
–10 V to +10 V. A bipolar signal extends between the negative and positive peak values of the
range.
You specify the range in software. Note that the range applies to the entire analog input
subsystem, not to a specific channel.
The DT3001, DT3002, DT3003, DT3004, and DT3005 boards provide gains 1, 2, 4, and 8; the
DT3001-PGL and DT3003-PGL boards provide gains of 1, 10, 100, and 500. Gains on all
DT3000 Series boards are programmable per channel.
Table 4 lists the effective ranges
supported by DT3000 Series boards using these gains.
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