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Keithley 2110 Digital Multimeter: Specs and What to Check

Quick answer: The Keithley 2110 is a 5½-digit, dual-display digital multimeter from Keithley Instruments (now part of Tektronix). The manufacturer’s datasheet lists a 0.012% basic DC voltage accuracy and 15 measurement functions. Its safety rating is the part to read carefully: the datasheet we opened does not state a CAT rating, and the Chinese-language reference manual we opened lists CAT II 600 V.

Quick answer

• Type: 5½-digit benchtop and portable digital multimeter with two lines of display.
• Stated basic DC voltage accuracy: 0.012% for the 100 mV to 100 V ranges, 0.02% for 1000 V (Keithley datasheet, one-year, 23 °C ±5 °C).
• Interfaces: TMC-compliant USB 2.0 standard; GPIB available as a separate model option.
• Check before buying: the CAT rating for your circuit, the speed you need at 5½ digits, and whether you need GPIB.

What the Model 2110 is built to measure

The Keithley datasheet describes the Model 2110 as a low-cost 5½-digit meter for system, bench, or portable use. It lists 15 measurement functions and 7 math functions, and it has a dual-line display that can show two different readings at once. The functions named in the datasheet are DC voltage, AC voltage, DC current, AC current, two-wire and four-wire resistance, frequency, capacitance, thermocouples, RTD and NTC thermistor temperature, diode tests, and continuity.

The stated ranges are useful when you compare it with a handheld meter. DC voltage runs from 0.1 V to 1000 V, and AC voltage runs from 0.1 V to 750 V. DC current has ranges from 10 mA up to 10 A, and AC current has 1 A, 3 A, and 10 A ranges. Resistance goes from 100 Ω up to 100 MΩ. Frequency is listed from 10 Hz to 300 kHz, and capacitance from 1 nF to 100 µF. These are the figures in the datasheet, not a summary of how the meter performs in your own setup.

Accuracy: what the number means

The headline accuracy in the datasheet is 0.012% for basic DC voltage. The datasheet writes this as a percentage of reading plus a percentage of range, and the exact term depends on the range. For example, the 100 mV and 1 V ranges are specified as 0.012% of reading plus 0.004% and 0.001% of range. At 1000 V the term rises to 0.02% of reading plus 0.003% of range. The datasheet states these figures are valid after a two-hour warm-up, and it lists a separate temperature coefficient for operation outside 18 °C to 28 °C.

Two points matter for a buyer. First, the figure is a one-year specification at 23 °C, so it describes the meter’s stated limit rather than a typical reading. Second, the accuracy you get in a real setup also depends on your leads, your connections, and the range you select. The datasheet does not cover those conditions for your specific bench.

Speed: the number in the headline is not the speed at 5½ digits

The Keithley datasheet headline says “up to 50,000 readings per second.” The same datasheet explains that figure applies at the 4½-digit fast setting. At 5½ digits, the datasheet says the Model 2110 delivers up to 200 readings per second over the USB remote interface. The FAQ from Keithley gives a table of buffered reading rates by number of power-line cycles (NPLC). At 0.001 NPLC the table lists about 49,200 readings per second, and at 1 NPLC it lists 60 readings per second for a 300-sample buffer.

This matters if you plan to use the meter for production testing. Pick the digit count and integration time first, then check the speed table for that setting. Do not buy on the headline number alone.

Safety rating: read this before you connect it to a circuit

The safety rating is where a buyer most needs to slow down. The datasheet we opened lists its voltage limits, but it does not state a CAT (measurement category) rating. The Chinese-language reference manual, Keithley document 2110-901-03 Rev. C, dated August 2013, lists the Model 2110 as CAT II 600 V in its safety text. We did not find a separate English safety section in the copies we opened, so treat the CAT II 600 V figure as the one the manual states and confirm it with Keithley for your model.

CAT II is the category for circuits such as the wall outlet and the devices plugged into it. It is not the category for the main panel, a sub-panel, or a permanently wired motor. A CAT II rating does not make the meter suitable for work on a service panel. Mains work is dangerous, and panel or service work belongs to a licensed electrician. The datasheet describes the meter for bench, system, and portable use and does not list a mains rating, so check the rating for your exact model before connecting it to anything at mains voltage.

The datasheet lists safety test leads and a power cable among the accessories included with the meter. Check that the leads supplied with your unit carry a rating that suits the work you plan to do. The datasheet does not state the lead rating, so do not assume it.

Interfaces and software

The datasheet says the Model 2110 has a TMC-compliant USB 2.0 interface that accepts SCPI commands, and it lists GPIB as an option for system use. Keithley also supplies utilities that graph readings and export data to Microsoft Word and Excel. These help with setup and checkout, but they do not change the meter’s measurement specification.

If you already run SCPI scripts from another Keithley instrument, the datasheet says the 2110 uses the same command style. If you run a system with many instruments, confirm which interface your PC and rack need before you order.

Who the Model 2110 suits

From the datasheet, the Model 2110 is aimed at production, research, service, calibration, and teaching work on bench or in a system rack. It is not a clamp meter, and it does not replace a non-contact voltage tester. If your work is a home outlet check, a car battery test, or a quick continuity check on a fuse, a handheld meter with a CAT rating printed on its case is usually the better fit. For a related read on choosing a meter, see our true RMS multimeter guide.

How we chose

This is a model explainer, not a ranking. We read the Keithley datasheet, the Keithley FAQ, and the Chinese-language reference manual, and we wrote down the figures each one states. We did not include figures from distributor pages, and we did not include any claim we could not match to one of the documents we opened. The copies we used are third-party hosts of Keithley’s documents, so the document numbers and revisions above are the ones printed in those copies.

What we could not verify

• The English-language safety section and CAT rating for the 2110 in the official English manual. The copy we opened is in Chinese.
• Whether your unit ships with the same leads or a different rating.
• Typical performance in your own setup. The datasheet gives specifications and conditions, not measurements from your bench.
• Current pricing, stock, or lead times. These are not part of this explainer.

FAQ

Is the Keithley 2110 a true RMS meter?

The datasheet we opened lists AC voltage and AC current as measurement functions but does not state the AC measurement method. If true RMS matters to you, read the AC section of the reference manual or ask Keithley to confirm the method for your model. For the meaning of the AC and DC markings on a meter, see our guide to reading multimeter symbols.

What is the basic DC voltage accuracy?

The datasheet states 0.012% basic DC voltage accuracy for most ranges and 0.02% at 1000 V, measured at 23 °C plus or minus 5 °C for one year after a two-hour warm-up.

Does the 2110 come with GPIB?

Not on every model. The datasheet lists USB as the standard interface and GPIB as an option. The ordering table shows separate part numbers with and without GPIB.

Is it safe to measure mains voltage with it?

The reference manual we opened lists CAT II 600 V. CAT II covers devices plugged into a wall outlet. It does not cover a service panel or a permanently wired circuit. For panel or service work, use a meter rated for that category and hire a licensed electrician.

How fast can it read?

At 5½ digits the datasheet says up to 200 readings per second over USB. The 50,000 readings per second figure applies at the 4½-digit fast setting.

Does it measure temperature?

Yes. The datasheet lists thermocouple types B, C, E, J, K, N, R, S, and T, and RTD and NTC thermistor measurements.

Bottom line

The Keithley 2110 is a 5½-digit bench meter with a stated 0.012% basic DC voltage accuracy and a wide set of functions. Before you buy, confirm the CAT rating for your model, check the 200 readings per second limit at 5½ digits, and decide whether you need the GPIB option. If the meter will be used on mains, make sure its rating and your leads suit that circuit.

Sources

• Keithley Instruments, Model 2110 5½-Digit Dual-Display Digital Multimeter datasheet (copy hosted on xdevs.com: https://xdevs.com/doc/Keithley/2110/2110%20DMM%20DataSht_HR.pdf). Opened 2026-10-27. Third-party copy of a manufacturer document; no document number printed in the copy.
• Keithley Instruments, Model 2110 Frequently Asked Questions (copy hosted on xdevs.com: https://xdevs.com/doc/Keithley/2110/2110%20FAQ%20AskedQuestions.pdf). Opened 2026-10-27. Third-party copy of a manufacturer document.
• Keithley Instruments, Model 2110 Reference Manual, document 2110-901-03 Rev. C, August 2013, Chinese-language (copy hosted on xdevs.com: https://xdevs.com/doc/Keithley/2110/2110-901-03%20%28C%20-%20Aug%202013%29%28Ref%29%28Chinese%29.pdf). Opened 2026-10-27. Third-party copy of a manufacturer document.