How to select a digital multimeter?
Resolution refers to how accurately a meter can make measurements. By knowing the resolution of your meter, you can determine whether it is possible to see small changes in the signal being measured. The terms digit and count are used to describe the resolution of a meter. DMMs are grouped by the count or number they display. 3½ digit gauges can display three full digits ranging from 0-9 to one-half digits, the latter displaying only a "1" or leaving it blank. The 3½-digit gauge can display up to 1,999 counts, while the 4½-digit gauge can display up to 19,999 counts. Some DMMs may have enhanced resolution to provide higher counts across their digital range.
Accuracy is the maximum allowable error in the reading. This shows how close the DMM's displayed measurement is to the actual value of the signal being measured. Accuracy is usually expressed as a percentage of reading. An accuracy of one percent of the reading means that for a display of 100 volts, the actual value of the voltage could be between 99 and 101 volts.
Autoranging (or "dial") is a useful feature that allows the user to quickly move from the instrument's various measuring scales while maintaining accurate readings.
