National Instruments 700 - Manual (Page 18)

Installation and Configuration Chapter 2
DAQCard-700 User Manual 2-4 © National Instruments Corporation
Table 2-2. Analog Input Modes for the DAQCard-700
Analog Input
Modes
Description
RSE Referenced single-ended mode provides 16 single-ended inputs referenced to
analog ground (default setting).
DIFF Differential mode provides eight differential inputs with the positive (+) input
of the instrumentation amplifier tied to channels 0, 1, 2, 3, 4, 5, 6, or 7 and
the negative (-) input tied to channels 8, 9, 10, 11, 12, 13, 14, or 15,
respectively, thus choosing channel pairs (0, 8), (1, 9), (2, 10), (3, 11),
(4, 12), (5, 13), (6, 14), or (7, 15).
While reading the following paragraphs, you may find it helpful to refer to the Analog Input
Signal Connections section of Chapter 3, which contains diagrams showing the signal paths for
the two configurations. These two modes are software selectable.
RSE Input (16 Channels, Default Setting)
RSE input means that all input signals are referenced to a common ground point that is also tied
to the DAQCard-700 analog input ground. The RSE configuration is useful for measuring
floating signal sources. See the Types of Signal Sources section of Chapter 3 for more
information. With this input configuration, the DAQCard-700 can monitor 16 different analog
input channels.
Considerations for using the RSE configuration are discussed in Chapter 3, Signal Connections.
Notice that in this mode, the return path of the signal is analog ground at the connector through
the AIGND pin.
DIFF Input (Eight Channels)
DIFF input means that each input signal has its own reference, and the difference between each
signal and its reference is measured. The signal and its reference are each assigned an input
channel. With this input configuration, the DAQCard-700 can monitor eight differential analog
input signals.
Considerations for using the DIFF configuration are discussed in Chapter 3, Signal Connections.
Notice that the signal return path is through the negative terminal of the instrumentation
amplifier and through channel 8, 9, 10, 11, 12, 13, 14, or 15, depending on which channel pair
you select.