CALCulate:FUNCtion NULL CALCulate:STATe ON CALCulate:NULL:OFFSet <value>

Removing Field

Wiring Resistance

Errors

in 2-Wire Ohms

Measurements

Field wiring can cause an offset error in 2-wire resistance measurements. You can use the following procedure to minimize offset errors associated with field wiring resistance in 2-wire ohms measurements. You short the field wiring at the DUT location and measure the 2-wire lead resistance.

This value is subtracted from subsequent DUT 2-wire ohms measurements. There are two ways to effectively null out the lead resistance. The first way is to characterize your field lead resistance by shorting the leads at the DUT location and measure and record the lead resistance. Then enable the math operation and store the 2-wire lead measurement value using the CALCulate:NULL:OFFSet <value> command (CALC:STATe must be ON to do this).

The following program shows SCPI examples used to store a NULL value.

CONF:RES

Set to 2-wire ohms function.

Short the lead resistance at the DUT location.

READ?

Measure the 2-wire ohms lead resistance.

Enter lead resistance value into computer.

Set math operation to NULL. Turn math operation ON. Store the NULL offset value.

Subsequent 2-wire ohms measurements will subtract the null offset value from the measurement thereby removing the lead resistance from the measurement.

The second way to store the 2-wire lead resistance as the NULL offset value is to let the multimeter automatically do this with the first measurement. The first measurement made after CALCulate function is set to NULL and the STATe is set to ON stores the measured value as the null offset.

CONF:RES

Set to 2-wire ohms function.

Short the lead resistance at the DUT location.

CALCulate:FUNCtion NULL

Set math operation to NULL.

CALCulate:STATe ON

Turn math operation ON.

READ?

Measure the 2-wire ohms lead resistance.

Enter lead resistance value into computer. The value is automatically stored in the multimeter’s null offset register.

Remove the short from the lead resistance at the DUT location and connect leads to your DUT.

READ?Make a 2-wire ohms resistance measurement. Enter lead resistance value into computer. The NULL value is subtracted from the measurement to more accurately provide the

DUT resistance.

30 HP E1312A/E1412A Multimeter Application Information

Chapter 2