The PCB Assembly Test Toolkit for LabVIEW includes three DMM Scan libraries to support a broad range of hardware configurations.

The following figure describes the general software structure and configuration used for all DMM_Scan libraries.


  1. By default, during the initialize function, all shunt channels are closed to maintain continuity of current to power the DUT.
  2. Each element (channel, function, range, digits) from the scan list is selected sequentially in the main loop.
  3. The mux channels for voltage-type functions are closed based on the corresponding path.
  4. If the channel is a current-type, the shunt channel is open to enable DMM current measurement.
  5. The shunt channel is closed to maintain continuity between scans.
  6. The mux channel is open.
Two optimizations are executed:
  • Do not open or close the shunt channel relay for voltage-only functions.
  • Do not reconfigure the DMM if the next channel configuration is the same. Execute the measurement using the existing configuration parameters.
For a scan list where functions and ranges are grouped to enable optimization, you may save several milliseconds. To precisely calcuate the total reduced time, consult your DMM specifications and relay operation time values specified in your switch specifications or external relay documentation.