Signal Paths
In Hardware-in-the-Loop (HIL) systems, a signal path refers to the complete physical and logical route a signal takes — either from the Device Under Test (DUT) to the acquisition hardware, or from a signal generation source back to the DUT. Each path is defined by the hardware components it traverses and the I/O capabilities required to support specific types of operations.
Signal paths are built around distinct I/O categories, each serving different testing needs.
Discrete I/O
Used for simulating or measuring basic electrical states or values:
- Analog I/O
- Digital I/O
- PWM (Pulse Width Modulation)
- Resistor Simulation
Communication Buses
Enable simulation or interfacing with automotive and industrial communication protocols:
- CAN, LIN, FlexRay
- Automotive Ethernet, RS485, EtherCAT, Standard Ethernet
Instrumentation I/O
Support high-precision signal generation and measurement:
- Digital Multimeters (DMMs)
- Oscilloscopes
- Function Generators
- Network Analyzers
- Signal Generators
Technical Parameters
Each I/O type is characterized by a set of specifications that influence system performance:
- Channel count
- Voltage/current range
- Impedance
- Bandwidth
- Sample rate
- Resolution
- Accuracy
- Isolation
Implementation in NI HIL Systems
In National Instruments (NI) HIL platforms, these signal paths are typically implemented using PXI modules; modular, high-performance components tailored for automotive and industrial test environments. PXI provides scalable and flexible I/O integration, enabling precise control and measurement across diverse signal types.