Fault Insertion Units

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Edition Date: April 2015

Part Number: 375472H-01

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Fault insertion units (FIUs) are designed to insert fault conditions between automated test equipment, such as hardware-in-the-loop (HIL) simulation systems, and devices under test (DUTs). The following figure represents how a FIU would be used in a complete test system.

To insert fault conditions, internal relays are configured to create short-circuit connections and open circuits.

Automated test applications commonly use the following fault conditions:

FIUs with switchable fault bus inputs can be used to create additional fault conditions, such as a pin-to-pin short through a load.

No-Fault Operation

In an FIU’s no-fault setting, test equipment is directly connected to DUT signal lines through the FIU module. The following figure shows a no-fault operation.

Open Circuit Faults

In an open circuit or interrupt fault, the signal line between the test application and DUT is left open to determine how the DUT behaves after a signal interruption. The following figure shows an open circuit or interrupt fault.

Short to Ground or Short to Power

To simulate shorts to ground or power, the signal line is connected from an external fault line or fault bus to the DUT. The fault buses can be configured to simulate power supply lines or system ground. The following figures represent a short to ground and short to power.

Pin-to-Pin Short

In a pin-to-pin short, the DUT signal line is connected to one or more additional DUT signal lines. The following figure shows a pin-to-pin short.

Example Pin-to-Pin Short Through a Load Using the NI PXI-2510

The NI PXI-2510 has two fault buses. Each fault bus has four switchable inputs to select among multiple fault conditions such as battery voltage (Vbatt), ground (GND), and other fault voltage potentials. The non-switchable input to each fault bus is intended for monitoring the fault bus with a DMM. The switchable fault bus inputs allow for another fault condition: a pin-to-pin short through a load.

The following example shows a pin-to-pin short through a load using the NI PXI-2510:

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