CHAPTER 4 ■ DIGITAL MULTIMETERData Interface
A data interface (see Figure 4-11) communicates measurements to a personal computer or external device.
This can be very useful for generating test logs. However, since the data from a multimeter is updated only a
few times per second, this feature can’t be used to make a multimeter into a true oscilloscope.
Figure 4-11. Connecting a multimeter to a personal computer with RS-232 DB9 (left) or optical USB (right)
Check to see if the computer software is included. If available separately, consider purchasing the
software at the same time as the multimeter, just in case the software becomes unavailable when that
multimeter model is discontinued.
Only some multimeters have the data interface feature.
Scope
A scope mode graphically plots measured values over a period of time. This can be an extremely useful
feature for examining the quality and grouping of data pulses and timing signals. There are pocket DMM
scopes with small color displays that can be handy even though speed and screen space is limited. However,
they are not a complete substitute for a true, high-speed oscilloscope with a large display and fast sample
rate. Few multimeters have a scope feature.
Backlight
A backlight lights up the meter’s display from behind. A backlight is useful at night, in dimly lit areas, or for
low contrast displays. When turned on, the meter’s battery drains much faster and some older units can emit
a high-pitched whine detectable by people with sensitive ears. Mainly higher-end or graphic-intensive units
have backlighting.
Stopwatch/Single Pulse Width
A stopwatch measures the time between events. It can be useful for checking circuit timing or servo
commands. Few multimeters have this feature.