Using Multiplexer Switching to Test Multiple DUTs

Use the BCQ Switch API to sequentially test multiple DUTs in multiple test jigs using one SMU or one DMM.

Introduced in Battery Cell Quality Toolkit 2025 Q3

Figure 6. Multiplexer Switching Topology Example


The BCQ Switch API simplifies the switching process between the different jigs. In addition, the BCQ Switch API automates the test flow using a switch configuration file and a simplified API. You can use the BCQ Switch API for EIS, ACIR, and OCV tests.

Before you begin, create the following configuration files:
  • Switch configuration file. Create a switch configuration file if you are performing an EIS or an ACIR test with switching. In Write Switch Configuration File.vi, define the following parameters:
    • Channel connections, including switch channels, for the DUT
    • Switch topology
    • DUT serial number
    • Jig ID
    Note Use one switch configuration file for the DUTs you are testing on one SMU. If you use multiple SMUs for simultaneous testing, create a separate switch configuration file for each SMU.
  • If desired, a test configuration file. Refer to Creating a Configuration File for Tests to learn how to create a configuration file. If you choose to use a test configuration file, your test runs according to the Frequency Sweep Characteristics you defined in the configuration file.

Equipment

Table 13. Required Equipment for Multiplexer Switching
Test Type Required Equipment
EIS or ACIR
  • SMU—PXIe-4139
  • Source switch—PXIe-2525
  • Sense switch—PXI-2530B
OCV
  • DMM—PXIe-4081 or PXI-4071
  • Switch—PXIe-2525 or PXI-2530B

Supported Switch Topologies

The BCQ Switch API supports the following switch topologies:

  • 2-Wire 64x1 Mux
  • 2-Wire Dual 32x1 Mux
  • 2-Wire Quad 16x1 Mux

Because all of the DUT, SMU, and DMM terminals are two wired, 2-wire topologies are suitable for cell testing with the Battery Cell Quality Toolkit.

NI recommends using the 2-wire, quad 16x1 mux topology. This topology allows you to use four separate terminal blocks when you use the recommended cables. Each of the terminal blocks contains 16 channels, tested sequentially. Because the terminal blocks operate separately, extra shielding and common wiring are not required between the terminal blocks.

The recommended topology allows you to use four SMUs or four DMMs simultaneously. You can use four modules simultaneously by using each group of 16 channels separately. To use the BCQ Switch API this way, create separate switch configuration files for each group of channels.

Complete the following steps to use multiplexer switching to test multiple DUTs.
  1. Use the NI Example Finder to open <Test type> Test with Switching.vi.
    1. In the LabVIEW window, select Help » Find Examples.
      The NI Example Finder window loads.
    2. Select Toolkits and Modules » Battery Cell Quality<Test type> Test with Switching.vi.
      The front panel of the VI loads.
  2. On the front panel of <Test type> Test with Switching.vi, select the SMU resource or the DMM resource from the HW Resource Name and Channels control.
    OptionDescription
    SMU resource Select the SMU resource for EIS tests and ACIR tests.
    DMM resource Select the DMM resource for OCV tests.
  3. Optional: If you want the SMU or DMM to perform self-calibration, enable self-calibration on the front panel.
    Note You must disconnect the DUT during self-calibration. If the DUT is connected to the SMU during self-calibration, an error occurs.
  4. Select a Source Switch Resource Name.
  5. Select a Sense Switch Resource Name.
  6. Select a Switch Configuration File Path.
    Select the switch configuration file you configured before you began. Alternatively, navigate to C:\Users\Public\Documents\National Instruments\NI-Cell Quality Toolkit\Samples and select the Switch Configuration.json example switch configuration file.
  7. Click Run.
After running <Test type> Test with Switching.vi, view the following results:
Table 14. <Test type> Test with Switching.vi Results by Test Type
Test Type Available Results
EIS and ACIR
  • Measured frequency (Hz)—The frequency transmitted by the SMU.
  • Impedance (Ohm). The toolkit calculates the impedance from the following values:
    • Z (Ohm)—The modulus of the impedance.
    • R (Ohm)—The resistance.
    • X (Ohm)—The reactance.
    • Theta (degrees)—The phase between the voltage and the current. Voltage is assumed to be at a zero angle.
EIS additional results
  • Cole-Cole plot—The impedance values at different frequencies. Each line on the plot represents the results of one DUT. Use Add Cell Serial Number or Jig ID to EIS Plots Legend.vi to identify the DUT and jig to which a plot belongs.
    • The x-axis represents the real part of the impedance, which is the resistance.
    • The y-axis represents the imaginary part of the impedance, which is the reactance.
  • Magnitude graph—The impedance (Ohms) for different frequencies (Hz).
  • Phase graph—The phase angle for difference frequencies (Hz).
OCV OCV (V)