Signal Connection Example - National Instruments NI USB-6525 User Manual And Specifications

Vcc
Digital
Logic
Computer
Ground
Isolation
USB-6525
Caution Use twisted-pair field wiring to reduce EMC noise.
Power supplies must be within the USB-6525 device range. Refer to the
Note
Specifications
USB-6525 User Guide and Specifications
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Applying a DC voltage of at least 3.2 V across two input terminals registers
logic high. Applying no voltage or a voltage difference of 1 V or less
registers logic low. DC voltages between 1 V and 3.2 V may not register a
consistent or usable value.

Signal Connection Example

Figure 5 shows signal connections for a power supply and load connected
to an isolated input.
MOSFET-Based
Current-Limiting
Circuitry
Schottky
Figure 5. Connecting a Power Supply and Load to the Isolated Input
In Figure 5, the USB-6525 is sensing a powered load that is connected to
the power supply through a switch.
section for information about these ranges.
When the switch is open, no current flows through the load and no voltage
is applied to the load or to the USB-6525 input. The digital logic of the
USB-6525 then registers a logic low for the channel. When the switch is
closed, current flows through both the load and the USB-6525 optocoupler,
and the USB-6525 registers a logic high for the channel.
P1. x +
Twisted-Pair
Wiring
P1. x –
6
+
Vsupply
_
Load
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