MCC USB-2408 Series

USB-2408 and USB-2408-2AO

Both models have 16 single-ended or 8 differential inputs, 24-bit sigma-delta conversion, eight ranges from ±10 V down to ±0.078 V, and up to eight channels set up for thermocouples. The USB-2408-2AO adds two 16-bit analog outputs with a ±10 V range, updating at up to 500 S/s per channel, or 1 kS/s on one output. Both have 8 digital I/O lines and two 32-bit counters rated to 1 MHz. Digilent’s store lists only the USB-2408-2AO now, at $830 at the time of writing.

Sample rate and noise

The 1 kS/s figure is aggregate across the scan. The converter offers data rates from 3,750 S/s down to 2.5 S/s, and on a sigma-delta part the slower rates give lower noise. Eight thermocouples lose nothing at a slow rate. For voltage channels, pick the slowest rate that still covers your signal. Isolation is 500 VDC minimum between field wiring and USB, which helps on test articles with their own ground. ADC resolution vs accuracy explains why a 24-bit label does not mean 24 noise-free bits.

Operating system support

MCC lists Windows and Linux support, with InstaCal, the Universal Library, TracerDAQ and DAQami on Windows. MCC’s uldaq library supports both the USB-2408 and USB-2408-2AO on Linux and macOS, from C or Python. The thermocouple calculator helps sanity-check readings during setup. DAQAtlas, which is in development, reads both models through uldaq, with thermocouple and voltage channels on the same dashboard.