Understand Sample Rate and Conversion Time in NI-9207

Updated Sep 22, 2026

Reported In

Hardware

  • NI-9207

Issue Details

I am evaluating the NI-9207 voltage and current input module.
The product page specifies a sampling rate of 500 S/s, while the specifications document lists a Conversion Time value instead of a traditional sample rate specification.
I need to understand how the sampling performance is affected when multiple channels are enabled and how to interpret the 500 S/s specification.
Specifically, I would like to know:
  • The maximum sample speed when using only one or two channels.
  • The per-channel sample speed when all 16 channels are used.
  • The meaning of the 500 S/s in the product page and the 2 ms in the specification sheet(High-Speed Mode).
  • Whether the specified rate includes channel-to-channel delay.

Solution

NI-9207 uses a Delta-Sigma ADC architecture with a multiplexer (MUX). The specified 500 S/s corresponds to a conversion time of 2 ms per sample.
  • Use 500 S/s as the aggregate module sampling rate.
  • Divide the aggregate rate by the number of enabled channels to determine the effective per-channel sampling rate.
Examples:
  • One channel enabled:
    • 500 S/s per channel
  • Two channels enabled:
    • 250 S/s per channel
  • 16 channels enabled:
    • 31.25 S/s per channel (500 รท 16)
The effective per-channel sampling rates already account for the conversion process and channel multiplexing behavior.
The specified 500 S/s (2 ms conversion time) represents the time required to acquire a single sample through the Delta-Sigma ADC measurement chain. This timing includes:
  • Oversampling
  • Digital filtering
  • Decimation
  • Multiplexer (MUX) switching and associated delay
Therefore, the published 500 S/s specification includes the channel-to-channel delay associated with the module's conversion process.

Additional Information

I have tested simple data acquisition using NI-9207+cDAQ-9171, and the sample qty was the same as expected.

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