Configurable ADC Timing

On the NI 9217, NI 9219, and NI USB-9219, you can configure high speed, high resolution, or low noise measurements using the ADC Timing Mode attribute/property. For the NI 9217 and NI 9219 in CompactDAQ, this attribute/property is set to High Resolution by default. To increase the conversion rate, set this attribute/property to High Speed. For the NI USB-9219, this attribute/property is set to High Resolution by default in on-demand mode, and the default value in hardware-timed mode is automatically determined based on Sample Clock Rate. To increase power line noise rejection on the NI 9219, set this attribute/property to Best 60 Hz Rejection or Best 50 Hz Rejection.

On the NI 9217, the ADC Timing Mode attribute/property affects both the maximum and default values for AI Convert Rate attribute/property in the DAQmx Timing property node. For instance, if the ADC timing mode corresponds to a conversion time of 200 ms, the maximum convert rate is 5 Hz.

Note  To set the set the convert clock rate for each device, you need to specify the active devices in the task and specify the AI Convert Rate attribute/property.

The ADC timing mode must be the same for all channels on the module, but may differ on multiple modules in the same task. On the NI 9219 and NI USB-9219, using a thermocouple or CJC channel increases the conversion time by 10 ms. Refer to your device documentation for the specific conversion rates.