User Manual

2400 Series SourceMeter

User’s Manual Ohms Measurements 4-3

Ohms measurement methods

NOTE For the Model 2430, the following ohms measurement procedures

assume that the DC Mode of operation is selected (“Vsrc” or “Isrc” dis

played in the source field). If in the Pulse Mode (“Vpls” or “Ipls” dis-

played), you can select the DC Mode by pressing CONFIG V or I,

selecting the SHAPE menu item, and then selecting DC. Pulse Mode

operation is covered in

Section 5.

There are two methods to measure ohms: auto ohms and manual ohms. When

using auto ohms, the SourceMeter operates as a conventional constant-current

source ohmmeter or DMM. To use this method, simply select an ohms measure-

ment range (or use autorange), and take the reading from the display. When

using auto ohms, the default test current varies with the ohms range, as summa-

rized in Table 4-1.

NOTE You cannot change the test current in the auto ohms mode. If you

attempt to change the source current in auto ohms, the SourceMeter will

display an error message.

With the manual ohms mode, you can select either source V or source I to make

ohms measurements, and the unit will automatically compute the resistance read-

ing using the V/I measurement method. After configuring the desired source and

selecting a voltage or current measuring range, select the Ω measurement

method to display the calculated V/I ohms reading.

NOTE To achieve optimum accuracy, the SourceMeter measures both V and I

and uses these values in ohms calculations (with source readback

enabled). The measured source value is more accurate than the pro

grammed source value. For remote operation, the user specifies the

functions to measure. See the resistance measurement accuracy specifi

cations in Appendix A.