Dataq DI-500 Series User Manual page 23

instrument channels by writing the letter from the grid in the box on the instrument panel overlay (i.e., place an "A"
in the box to designate slave channels A1 through A32).
If a second DI-500-16 is multiplexed as a slave to the first DI-500-16, enable all 32 channels on the top row of the
grid (no other expansion is permitted when two DI-500-16's are multiplexed). In this case, the expansion cable is con-
nected from the EXPANSION connector on the master to the AUXILIARY PORT connector on the slave.
Point to the box in the grid that represents the desired channel and click the left mouse button to enable the
channel as a differential input (when not using 5B modules) or as an input defined by the 5B module (when
used). A check mark is displayed in the desired channel box, indicating that a differential input (when not
using 5B modules) or an input defined by the 5B module (when used) has been enabled. A second activation removes
the check mark and thus disables the channel.
Point to the box in the grid that represents the desired channel and double-click the left mouse button to enable
a pair of differential channels for differential operation (this allows you to see the difference between 2 differ-
ential input channels). A plus sign (+) is displayed in the desired channel box, indicating one differential chan-
nel and a minus sign (-) is automatically displayed eight channels away (i.e., channels 1 and 9, 2 and 10, 5 and 13,
etc.), indicating the other differential channel. You can select the first or positive channel (from 1 through 8), but the
second or negative channel is automatically selected by the software. Clicking the left mouse button on the plus sign
removes both plus and minus signs and thus disables the channel pair.
This configuration is useful anytime you need to monitor the difference between two differential input channels. For
example, say you are monitoring the temperature of a long, narrow widget. You want the widget to be of uniform
temperature throughout its entire length. You could use two thermocouples (one per channel, on each end of the wid-
get) to monitor temperature. The temperature of one end of the widget would be measured by one thermocouple and
the temperature of the other end of the widget would be measured by the other thermocouple. However, in the differ-
ential channel pair configuration as described above, only the difference between the two thermocouples would be
reported by W D software. This difference in temperature could then be used to control a process (i.e., if one end
IN AQ
is 5° hotter than the other, then turn on a heater to evenly distribute the widget temperature).
Point to the box in the grid that represents the desired channel and click the right mouse button to enable the
channel as a digital input. An "I" is displayed in the desired channel box, indicating that a digital input has
been enabled. Pointing to the "I" and clicking the left mouse button removes the "I" and thus disables the
channel. The digital inputs are connected to the 37-pin AUXILIARY PORT connector on the DI-500-16 instrument.
Note that when you specify a channel as a digital input in the channel selection grid, you no longer have the ability to
connect an analog signal to that channel either at the sheathed banana jacks or at the screw terminals.
DI-500/510 Series and DI-750/760 Series Hardware Manual
Enabling Channels for Acquisition
17
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