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 IO capabilities required to support specific types of operations.
Signal paths are built around distinct IO categories, each serving different testing needs.
Discrete IO
Used for simulating or measuring basic electrical states or values:
- Analog IO
- Digital IO
- 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 IO
Support high-precision signal generation and measurement:
- Digital Multimeters (DMMs)
- Oscilloscopes
- Function Generators
- Network Analyzers
- Signal Generators
Technical Parameters
Each IO 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 IO integration, enabling precise control and measurement across diverse signal types.