Local Sense

NI DC Power Supplies and SMUs Help (NI-DCPower)

Edition Date: January 2018

Part Number: 370736U-01

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Measurements taken with local sense use a single set of leads for output and voltage measurement, as illustrated in the following figure.

When the device is operating in Constant Voltage mode, local sense forces the requested voltage at the output terminals of the device. The actual voltage at the DUT terminals is lower than the requested output because of the output lead resistance error.

The error in the DUT voltage measurement is due to the output current, the output resistance of the source (specified as load regulation), and the resistance of the leads used to connect the power supply or SMU to the load. This error can be calculated using the following equation:

Local Sense Error (Volts) =  Iout(Rlead1 + Rlead2 + Rout.source)

The output resistance of the source typically includes the effective resistance of protection circuitry in series with the sourcing path, and is usually negligible in comparison to external resistance. However, for high-current applications, you may notice the resistance of the protection circuitry. Remote sense measurements are more appropriate for high-current applications.

Using a Local Sense Hardware Configuration with a Remote Sense Channel Configuration

If the source has remote sense capabilities and a 2-wire configuration needs to be maintained, you can remove the effect of any protection circuitry in series with the sourcing path by configuring the channel for remote sense and connecting the sense terminals externally to their respective output terminals, as illustrated in the following figure.

Note Note  The NI PXIe-4112/4113 can be used with this local sense hardware configuration but support only remote sense in the NI-DCPower API. Refer to the NI PXIe-4112 Local and Remote Sense and NI PXIe-4113 Local and Remote Sense topics for more information.

Related Topics

Cabling and Current-Resistance Loss

NI PXIe-4112 Local and Remote Sense

NI PXIe-4113 Local and Remote Sense

Remote Sense

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