Operator`s manual

3.6 Using the Control Panel

Figure 3-2. The Control Panel for the SM2044. The three main groups include Measure, Source and

ange buttons. The 8 Range buttons are context sensitive such that only “330m, 3.3, 33 and 250 appear R

when in AC Voltage Functions, “3.3m 33m 330m 2.5” appear when in Current Functions, etc.

Note: All of the controls described below correspond to their respective software function, which can be invoked

within your control software or as objects in a visual programming environment. The software command language

of the SM2040 provides a powerful set of capabilities. Some of the functions are not included in the control panel,

but are in the software.

DC/AC This function switches between DC and AC. This is applicable for the following DMM functions:

Voltage, Current, and Voltage-Source. If Voltage-Source is the function presently in use, the Source control under

the Tools menu can be used to set frequency and amplitude in ACV, and amplitude only in DCV and DCI.

Relative This is the Relative function. When activated, the last reading is stored and subtracted from all

subsequent readings. This is a very important function when making low-level DCV measurements, or in 2WΩ.

For example, when using 2WΩ, you can null out lead resistance by shorting the leads together and clicking on

Relative. When making low level DC voltage measurements (e.g., in the µV region), first apply a copper short to

the V,Ω + & - input terminals, allow the reading to stabilize for a few seconds, and click on Relative. This will

correct for any offsets in to the SM2040. The Relative button can also be used in the Percent and dB

eviation displays (shown below), which are activated using the

ternal

ools in the top menu.

Signametrics 22

ate Box: Controls the SM2040 reading rate. 0.1 rps to 1,000 rps can be set

The Min/Max box can be used to analyze variations in terms of Min, Max, Percent and

dBV. This display can be activated by selecting the

Min/Max/Deviation from the Tools

menue. For instance, testing a circuit bandwidth with an input of 1V RMS, activate t

Relative function with the frequency set to 100Hz, than sweep gradually the frequency,

and monitor the percent deviation as well as the dBV error and capture any response

anomalies with the Min/Max display. The left display indicates peaking of 2.468%

(0.21 dBV) and maximum peaking in the response of +56.24mV and

a notch of –

10.79mV from the reference at 100Hz.

R . As measurement rate increases, so

sider

ote on Measurement Rate: All three products are capable of continuous measurement as well as data transfer

rates of up to 1,000 rps. To achieve the 6-1/2 digit resolution and accuracy, the DMM should be operated at 10 rps

or slower. The maximum reading rate for 5-1/2 digits is 30 rps.

Range: Can be set to AutoRange or manual by clicking on the appropriate range in the lower part of the

Windows panel. Autoranging is best used for bench top application and is not recommended for an automated test

does the measurement noise. For best accuracy set to the lowest rate acceptable for the application. Also con

the line frequency (50/60 Hz) of operation when setting reading rates, as certain reading rates have more noise

rejection at either 50 or 60 Hz. (See “Specifications” for details.) Set the measurement rate as low as practical for

the application. When measuring RMS values, there is no point setting the measurement rate to a value higher than

5 rps since the RMS circuitry has a settling time that is over a second. The capacitance function is not affected by

rate setting. For inductance measurements use 10 rps or slower measurement for best accuracy.