Internal Channels for the NI PXI-42XX
The following table is a list of internal physical channels for the PXI-42XX devices. The subset of channels present on your device depends on the specific E Series device being used. These channels are typically for self-calibration, and you can sample them as you would a physical channel present on the I/O connector.
| Internal Channel Name | Description |
|---|---|
| _cjTemp | A cold-junction compensation channel for measuring the temperature at the I/O connector when making thermocouple measurements. |
| _aignd_vs_aignd | A differential terminal with the positive terminal connected to the ground reference for analog input and the negative terminal connected the ground reference for analog input. |
| _caldac_vs_aignd | A differential terminal with the positive terminal connected to the onboard calibration DAC and the negative terminal connected to the ground reference for analog input. |
| _calref_vs_aignd | A differential terminal with the positive terminal connected to the onboard 5 V reference and the negative terminal connected to the ground reference for analog input. |
| _boardTempSensor_vs_aignd | A differential terminal with the positive terminal connected to the onboard temperature sensor and the negative terminal connected to the ground reference for analog input. |
| PXI_SCXIbackplane_vs_aignd | A terminal where a signal being conditioned by a SCXI module is measured across the PXI/SCXI backplane and not the I/O connector. Reading from this channel is valid only on PXI devices inserted in the rightmost PXI slot of a PXI/SCXI combination chassis. |
| _extcal_vs_aignd | A differential terminal with the positive terminal connected to the external calibration input and the negative terminal connected to the ground reference for analog input. |
| _pod_calrefPos_vs_aignd | A differential terminal with the positive terminal connected to the internal positive reference voltage and the negative terminal connected to the ground reference for analog input. |
| _pod_calrefNeg_vs_aignd | A differential terminal with the positive terminal connected to the internal negative reference voltage and the negative terminal connected to the ground reference for analog input. |