Selection of digital multimeters
1. Basic DC voltage accuracy
All kinds of signals measured in a digital multimeter will eventually be converted into a DC voltage type by the circuit for measurement.
Therefore, the basic DC voltage accuracy of the digital multimeter has become the most important technical indicator to measure the accuracy of the digital multimeter. And usually the DC voltage accuracy marked on the meter should be the annual accuracy.
2. Reading resolution
Indicates the effective reading resolution value that can be displayed on the screen of the digital meter, or it can be simply understood as the maximum number of digits after the decimal point that can be displayed on the screen when measuring small signals. For example, a six-and-a-half-digit digital multimeter usually displays a value of six digits after the decimal point when measuring 1V voltage.
3. Measurement type
Commonly used measurement types are AC and DC voltage, current, and resistance. Today's DMMs also provide capabilities such as capacitance, frequency, diode, continuity testing, arbitrary sensor measurements, and signal statistics.
4. Signal measurement range
For different models of digital multimeters, the measurement range is different. For example, the Agilent 34401A has a current range of up to 3A. If I want to measure a current of 9A, then I need to choose other models of digital multimeters. Please check the value range of frequently measured data before selecting.
5. Communication interface
The mainstream communication interface types of the digital meter are USB, GPIB, LAN, RS232. It is mainly used for the communication between the instrument and the computer, and it is convenient to transmit, save and analyze the measurement data in time. For example, it is more convenient to choose the LAN interface when the instrument is placed far away from the computer. If the meter is in close proximity and just needs to provide high-speed data transfer, then USB is handy. GPIB will be very convenient if it is conducive to system bus control integration.
