There are many factors which will affect the overall scanning speed of a DMM/switch system. The major factors include the type of the measurement, the range of the measurement, and resolution of the measurement. The effect of these and other factors related to the DMM can be better understood by considering the digital multimeter measurement cycle. In addition to these factors, relay operate times, DMM settling times, and switch settling times limit the overall speed of the system. The following benchmarks provide a good starting point to see typical scan rates for common use cases.
The benchmarking application that was used to gather the following data is attached to this document. There are two top level VIs within the library. The 2-Wire Resistance with DataLog VI uses the Microsoft Report Generation Toolkit to log the acquired scan rates to an MS Excel Spreadsheet. The2-Wire Resistance VI preforms the exact same scan rate test, but only displays the results rather than logging them to a file. Both top level VIs and all required subVIs are contained in the .llb file.
The NI-DAQmx API was used to program the switches in order to obtain these benchmarks. This program systematically cycles through each DMM resolution and range and logs all the resulting scan rates to a spreadsheet. The attached program is configured to make 2-Wire Resistance measurements, but can easily be used to benchmark scan rates for other measurement types and other devices.