PXIe-4051 Electronic Load Cannot Sink Current

Issue Details

When attempting to operate a PXIe-4051 Electronic Load, the module is unable to draw or sink current regardless of the programmed current setpoint (e.g., 10 mA or 2 A) or software settings in NI-DCPower, InstrumentStudio, or custom application code. 

Solution

The front panel of the PXIe-4051 includes an AUX I/O connector that provides access to digital signals, including the INHIBIT input on Pin 4.

When Pin 4 (INHIBIT) is disconnected, open, or floating (such as when the removable AUX I/O mating connector plug or wire harness is missing or improperly wired), the module is hardware-forced into an output-disabled state. In this state, the internal output/sinking circuitry is hardware-disabled, preventing the module from drawing power or current regardless of software commands.

To exit the inhibited state and restore normal current-sinking operation, Pin 4 (INHIBIT) on the AUX I/O connector must be shorted to a Ground (GND) reference by following below steps:

1. Power off the PXI Express chassis.
2. Check the AUX I/O header located on the front faceplate of the PXIe-4051 .
3. Ensure the removable AUX I/O connector plug is inserted into the AUX I/O port.
4. Wire or short Pin 4 (INHIBIT) to a Ground (GND) pin (such as Pin 8):
   • Use the pre-wired jumper plug/harness included with the PXIe-4051 connector kit.
   • Alternatively, for bench testing, connect a female-to-female jumper wire between Pin 4 (INHIBIT) and Pin 8 (GND) on the AUX I/O header.
5. Power on the chassis.
6. Verify hardware functionality using NI MAX Self-Test or test current load operation using InstrumentStudio or an NI-DCPower example program .

Once Pin 4 receives a continuous Ground logic signal, the PXIe-4051 exits the inhibited state and operates normally.