Enabling and Disabling ADC Channels

The NI-Motion Analog-to-Digital Converter (ADC) multiplexes between channels with a scan rate of approximately 40 µs for the 7340 motion controller, and 25 µs for the 7350 motion controller. Therefore, the time between samples for a specific ADC channel is as follows:

• 7330/40:  ADC sample time = 40 µs/channel x (number of enabled channels)
• 7350:  ADC sample time = 25 µs/channel x (number of enabled channels)

The 40 µs/channel scan rate is fast enough to support analog feedback at the fastest PID update rates as long as no additional ADC channels are enabled.