Solution
The following table is a list of internal channels for M Series devices. The subset of channels present varies by device. 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 |
| _aignd_vs_aignd | A differential terminal with the positive and negative terminals both connected to the ground reference for analog input. |
| _ao0_vs_aognd | A differential terminal with the positive terminal connected to physical channel ao0 and the negative terminal connected to the ground reference for analog output. |
| _ao1_vs_aognd | A differential terminal with the positive terminal connected to physical channel ao1 and the negative terminal connected to the ground reference for analog output. |
| _ao2_vs_aognd | (For M Series devices only.) A differential terminal with the positive terminal connected to physical channel ao2 and the negative terminal connected to the ground reference for analog output. |
| _ao3_vs_aognd | (For M Series devices only.) A differential terminal with the positive terminal connected to physical channel ao3 and the negative terminal connected to the ground reference for analog output. |
| _calref_vs_aignd | A differential terminal with the positive terminal connected to the internal calibration reference voltage and the negative terminal connected to the ground reference for analog input. |
| _aignd_vs_aisense | A differential terminal with the positive terminal connected to the ground reference for analog input and the negative terminal connected to physical channel AI SENSE. |
| _aignd_vs_aisense2 | A differential terminal with the positive terminal connected to the ground reference for analog input and the negative terminal connected to physical channel AI SENSE2. |
| _calSrcHi_vs_aignd | A differential terminal with the positive terminal connected to the calibration PWM and the negative terminal connected to the ground reference for analog input. |
| _calref_vs_calSrcHi | A differential terminal with the positive terminal connected to the internal calibration reference voltage and the negative terminal connected to the calibration PWM. |
| _calSrcHi_vs_calSrcHi | A differential terminal with the positive and negative terminals connected to the calibration PWM. |
| _aignd_vs_calSrcHi | A differential terminal with the positive terminal connected to the ground reference for analog input and the negative terminal connected to the calibration PWM. |
| _calSrcMid_vs_aignd | A differential terminal with the positive terminal connected to the calibration PWM and the negative terminal connected to the ground reference for analog input. _calSrcMid is the divided down version of _calSrcHi. |
These internal channels are routed using an internal switching matrix, so no wiring or cabling is required. Refer to
Internal Channels for M Series and NI 6010 Devices in in NI-DAQmx Help for more information on internal channels.