National Instruments NI TB-2709 Measuring Floating Signals

Figure 4. NI TB-2709 Block Diagram

For more detailed descriptions of these signals, refer to the S Series User

Manual.

Additional signal configuration information is available in Measurement &

Automation Explorer (MAX). To access this information in MAX, select

your device under Devices and Interfaces, and click the Device Routes

tab.

Measuring Floating Signals

You can use the TB-2709 to measure floating and ground-referenced

analog input signals. To measure floating signal sources, move the switch

located under the rubber-sealed door on the enclosure cover for the AI

channel you are using to the ON (floating source) switch position. In the

floating source switch position, the amplifier negative terminal connects to

ground through a 5kΩresistor in parallel with a 0.1 μF capacitor. Table 2

shows the TB-2709 switch configuration options.

Table 1. TB-2709 Signal Descriptions

Signal Name Reference Direction Description

AI<0..7> AI GND Input Analog Input channels 0 through 7.

PFI 0/AI Start Trig D GND Input As an input, this pin is a programmable

function input (PFI).

Output As an output, this pin is the AI Start

Trigger signal.

AI <0..7> +

AI <0..7> –

Front Panel

SMB Connectors

DAQ Device

Signals

AI <0..7> GND

AI Start Trig

D GND

5 kΩ

0.1 μF