The current sourcing sensor shown must be matched with a ____ PLC input module.

• A. Current sinking
• B. Current sourcing
• C. Voltage sinking
• D. Voltage sourcing

Answer: (A)

The test is about matching how the sensor outputs signal to how the PLC input expects to receive it so a complete current path is created. A current sourcing sensor pushes current out into the circuit. To make that current flow into the PLC input and return to ground, the PLC input must be able to sink current. That’s why a current sinking input module is the correct match—the input provides a path to ground for the sensor’s sourced current. If you used a current sourcing input instead, both sides would be sources and no proper current flow would occur, so the signal wouldn’t be detected.