2-5
Note:
Analog input channels on DAS-800 Series boards are provided
with protection against signals outside the specified analog input range.
All DAS-800 Series boards can tolerate voltages up to ±35 V and
transients of several hundred volts without damaging the board.
When measuring signals at differential inputs, DAS-801 and DAS-802
boards can tolerate common-mode voltages up to ±35 V and transients of
several hundred volts without damaging the board; however, for normal
operation of the board, make sure that the common-mode voltage is no
more than 12 V
−
((G / 2) x V
D
), where G is the gain and V
D
is the
differential input voltage.
Channel Selection
You can use DAS-800 Series boards to acquire data from a single analog
input channel or from a range of contiguous, on-board analog input
channels using automatic channel scanning. These two methods of
channel selection are described as follows:
●
Single channel - You use software to specify a single channel and
initiate a conversion.
●
Automatic channel scanning - You use software to specify the first
and last channels in a range of contiguous, on-board channels (0 to 7).
The channels are sampled in order from first to last; the hardware
automatically increments the analog input multiplexer address shortly
after the start of each conversion. When the last address is reached,
the multiplexer returns to the start address and the channels are
sampled again. For example, assume that the start channel is 4, the
stop channel is 7, and you want to acquire five samples. Your program
reads data first from channel 4, then from channels 5, 6, and 7, and
finally from channel 4 again.
The start channel can be higher than the stop channel. For example,
assume that the start channel is 7, the stop channel is 2, and you want
to acquire five samples. Your program reads data first from channel 7,
then from channels 0, 1, and 2, and finally from channel 7 again.
When using automatic channel scanning, all contiguous, on-board
channels must have the same gain (analog input range).
