Scope and Multimeter Operations Technical Specifications (Scope Module)
101
9.5.2 Digital Multimeter (DMM)
The digital multimeter gives you the ability to quickly make precise common
electrical measurements (e.g. DC and AC voltage, resistance and amperage) on
circuits and components to verify operation. The meter displays measurements in a
digital numerical format, and is typically used for measuring signals that are not
rapidly changing.
The DMM is ideal for performing basic tests on most standard automotive circuits,
and displays the results in a large easy to see format.
To use the DMM, select the Scope Multimeter icon from the home screen, then
select Digital Multimeter from the menu. See Tests and Capabilities (Quick
Reference) on page 99 for a list of available testing functions.
DMM Specifications
9.5.3 Graphing Multimeter (GMM)
Unlike the DMM, the graphing multimeter plots a visual graphing line of the signal
instead of displaying digital values. The GMM displays a signal’s measurements
over time on a two-dimensional grid. This plotted graph is basically a graphical
history (histogram) of the signal’s measurements over time.
The GMM uses a higher sample rate (than a DMM) to calculate signal
measurements. This characteristic along with the visual graph, make the GMM
ideal for finding intermittent dropouts or glitches that may not be obvious when
viewing a digital value. A key advantage of the GMM is being able to capture a
signal over a long time interval and then review it’s graphical history, to visually see
if and when dropouts have occurred.
In addition, the GMM uses a combination of filter and peak detect modes to provide
a good balance between detecting fast glitches and preventing unwanted noise
from displaying.
Unlike the lab scope, the sweep scales used with typical GMM tests are of longer
time intervals, and may range from seconds to minutes, compared to the lab scope
sweep scales that use relatively short time intervals (e.g. milli and microseconds).
This allows you to monitor a signal over a longer period of time when looking for
erratic glitches or dropouts.
To use the GMM, select the Scope Multimeter icon from the home screen then
select Graphing Multimeter from the menu. See Tests and Capabilities (Quick
Reference) on page 99 for a list of available testing functions.
Function Range Accuracy/Comments
Signal
Measurement
Ch. 1—yellow
jack
Channel 1 input is referenced to common ground
(GND—black jack)
VDC (Full Scale) 75VDC Do not measure greater than 75VDC
VAC (Full Scale) 50VAC Do not measure greater than 50VAC (rms)
Signal
Measurement Input
Impedance
10 MΩ -
Ohm Measurement
Diode Test
Continuity Test
Ch. 3—blue jack
Ch. 4—red jack
-
Ohms 40 Ω–4 MΩ Fixed scales or Auto Ranging
Glitch capture
Approximately
50 uS
-
Diode Test 2 V Scale -
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