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.