National Instruments Low-Cost Multifunction I/O Board for ISA Lab-PC+ - Manual (Page 41)

Signal Connections Chapter 3
Lab-PC+ User Manual 3-10 © National Instruments Corporation
Single-Ended Connection Considerations
Single-ended connections are those in which all Lab-PC+ analog input signals are referenced to
one common ground. The input signals are tied to the positive input of the instrumentation
amplifier, and their common ground point is tied to the negative input of the instrumentation
amplifier.
When the Lab-PC+ is configured for single-ended input (NRSE or RSE), eight analog input
channels are available. Single-ended input connections can be used when the following criteria
are met by all input signals:
1. Input signals are high-level (greater than 1 V).
2. Leads connecting the signals to the Lab-PC+ are less than 15 ft.
3. All input signals share a common reference signal (at the source).
If any of the preceding criteria are not met, using DIFF input configuration is recommended.
You can jumper-configure the Lab-PC+ for two different types of single-ended connections:
RSE configuration and NRSE configuration. The RSE configuration is used for floating signal
sources; in this case, the Lab-PC+ provides the reference ground point for the external signal.
The NRSE configuration is used for ground-referenced signal sources; in this case, the external
signal supplies its own reference ground point and the Lab-PC+ should not supply one.
Single-Ended Connections for Floating Signal Sources
(RSE Configuration)
Figure 3-5 shows how to connect a floating signal source to a Lab-PC+ board configured for
single-ended input. The Lab-PC+ analog input circuitry must be configured for RSE input to
make these types of connections. Configuration instructions are included under Analog Input
Configuration in Chapter 2, Configuration and Installation.