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|Document version||1.0, 04.01.2018|
A software tool and hardware to measure DriveTest test system current and voltage and create a calibration report.
DriveTest e-mail: info@DriveTest.de.
DriveTest Calibration Tool is a Windows software for easy current and voltage measurement of DriveTest Test Systems under changing load conditions. A calibration report in HTML file format is generated automatically by the software. Calibration Tool is used in combination with one or two IVI compatible digital multimeters and a cascade of load resistors.
The pictures below shows the simplified schematics of a complete current and voltage calibration setup. Calibration compares the internally measured current or voltage of the Unit Under Test with the externally measured values provided by the calibration device. Multiple current ranges can be examined by applying different Power Supply setpoint voltages and loads in the Load Box.
The Unit Under Test is the system which is supposed to be calibrated, e.g. a DriveTest Test System. It typically contains a Power Supply with programmable voltage and maximum current. A Switch device cuts the connection between power supply and load. It is possible to use Calibration Tool with systems containing a fixed voltage / fixed maximum current Power Supply and no Switch device.
Calibration Tool assumes that both Power Supply and Switch are controlled and monitored via National Instruments I/O modules. The physical I/O lines connected to power supply and switch are utilized by so called Global Virtual Channels, which are pre-configured with DriveTest test systems. Global Virtual Channels are managed by National Instruments software Measurement & Automation Explorer.
For current and voltage measurement resistive loads are applied to the test system. They are contained in a handy box with laboratory plugs, making it easy to apply a series of loads. The current flowing through the load resistor is measured via a shunt resistor.
The Calibration connector provides an easy way to connect load resistors via the Calibration Load Box and voltage probes. It can be directly plugged in to the standard DriveTest Test System Connector as a replacement for the Unit Under Test Adapter.
Calibration requires a reference measurement with an external trusted measurement device. To calibrate DriveTest test systems, one or two IVI compatible Digital Multimeters (DMM) for Windows PC connection are required. IVI is a standard driver abstraction for laboratory instrumentation. It enables Calibration Tool to access any DMM which comes with an IVI DMM driver.
Calibration Tool allows the configuration of a “Primary DMM” and a “Secondary DMM”.
DriveTest Calibration Tool is Windows 32bit software for Windows 7, 8 and 10. It comes as a regular Windows installer. Execute setup.exe and follow the instructions on the screen. DriveTest recommends to use default installation folders.
Calibration Tool requires National Instruments DAQmx Global Virtual Channels (“GVC”) to set and measure current and voltage output. Optionally, Calibration Tool can use GVCs to control a switch connecting the power lines to the Unit Under Test.
NI-DAQmx Global Virtual Channels in National Instruments Measurement & Automation Explorer Use National Instruments Measurement & Automation Explorer (“MAX”) to manage Global Virtual Channels. It installs with DriveTest Calibration Tool.
Use the table below to check in MAX if the required GVCs are available. Make sure the channels link to the proper physical channels.
|Purpose||DriveTest Standard Channel Name||Calibration Type||Necessity|
|Power Supply Voltage Setting||Power_Supply_Voltage||Current, Voltage||Required|
|Power Supply Current Setting||Power_Supply_Current||Current, Voltage||Required|
|Power Supply Voltage Output||Power_Supply_Voltage_Mon||Current, Voltage||Required|
|Power Supply Current Output||Power_Supply_Current_Mon||Current||Required|
|Power Switch Control Input 1||Power_Switch_1||Current, Voltage||Optional|
|Power Switch Control Input 2||Power_Switch_2||Current, Voltage||Optional|
To create a new Global Virtual Channel, right click “NI-DAQmx Global Virtual Channels” in the left hand side navigation tree and select “Create new DAQmx Channel…”.
If the default channels need to be adapted, select the channel in the left hand side navigation tree. In the configuration pane on the right hand side, right click the channel name and select “Change Physical Channel”.
DriveTest Calibration Tool relies on a hardware abstraction scheme called IVI to communicate with the Primary and Secondary DMM. This allows you to use any IVI compatible device which supports the IVI DMM class.
With installation, Calibration Tool brings support for National Instruments USB-4065 and HP / Agilent / Keysight 34401A. It can be necessary to adapt the Resource Descriptor, that is the device name (“Dev1”) or the COM Port, in the IVI Driver Session in NI MAX at the location seen in the screenshot below (usb4065 respectively).
A detailed description how to set up IVI with NI MAX can be found on the National Instrument website: Using Measurement & Automation Explorer to Configure Your IVI System