USB Digital Multimeter - Auto-Ranging (RS232 Output)

It seems like everything plugs in to your computer these days, and this digital multimeter is no exception. This auto-ranging multimeter will test AC and DC voltage and current as well as capacitance, resistance, frequency and even temperature. It features a large, easily readable display for use in the field as well as the ability to connect to your computer for data logging, processing and analysis. It has all of the basic functions that you expect from a good digital multimeter including continuity check (with buzzer), diode test and data hold. Data logging and analysis software is included on a mini-CD and you can also download it below.

Note: The included CD contains all versions of the software. The version that has been tested to work with this unit is version 3.0. You can also just use the download link in the Documents Tab.

Note: This meter does have a USB interface, but it's not clearly RS232. The meter needs the proprietary software to function and you cannot simply read the data directly without a driver and the software.

  • User Manual
  • Test Leads
  • Temperature Probe
  • 2 x "AAA" 1.5V Batteries
  • Software CD
  • USB Cable
  • Auto-Ranging
  • Shockproof Protection
  • Input Impedance: 10MΩ
  • Relative Value Measurement
  • 70×50mm LCD Display
  • AC Frequency response: 40-400 Hz
  • DC Voltage Ranges: 400mV/4V/40V/400V/1000V ±(0.5%+4)
  • AC Voltage Ranges: 400mV/4V/40V/400V/750V ±(0.8%+10)
  • DC Current Ranges: 30mA/300mA/10A ±(1.5%+10)
  • AC Current Ranges: 30mA/300mA/10A ±(1.5%+10)
  • Resistance Ranges: 400Ω/4kΩ/40kΩ/400kΩ/4MΩ/40MΩ ±(0.8%+4)
  • Capacitance Ranges: 4nF/40nF/400nF/4uF/40uF/200uF ±(3.5%+8)
  • Frequency Ranges: 100Hz/1000Hz/10kHz/100kHz/1MHz/30MHz ±(0.5%+10)


USB Digital Multimeter - Auto-Ranging (RS232 Output) Product Help and Resources

How to Use a Multimeter

January 9, 2015

Learn the basics of using a multimeter to measure continuity, voltage, resistance and current.

Replacement Fuses

Unfortunately, SparkFun does not carry replacement fuses for this multimeter but here are links to where you can find them:

600mA: Mouser Part #: 576-0235.600HXP

10A: Mouser Part #: 576-0217010.MXP

Software and Drivers

The included CD has the software to use with this multimeter. The install should also have the drivers. When connected via USB the device should enumerate as "Silicon Labs CP210x USB to UART bridge (COM##)".

Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

2 Electrical Prototyping

Skill Level: Rookie - You may be required to know a bit more about the component, such as orientation, or how to hook it up, in addition to power requirements. You will need to understand polarized components.
See all skill levels


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • hydronics / about 6 years ago * / 1

    will this diode tester light up an LED?

    I have one meter that can do this but haven't found another in years... at my $70 price point..

    "A digital multimeter with a Diode Test function can be used to test LEDs of various colors if the DMM applies a sufficient voltage potential at the meter leads to overcome the forward voltage requirement of the LED. The Diode Test function typically applies 2 mA of current to the diode under test. This current along with enough voltage to overcome the forward bias requirement is usually enough to illuminate most LEDs."

    Most DMM are around 1.5V and fall short of the 2.5-3V you really want. The literature for this multimeter under diode testing says, "Forward DC current is about 1.0mA, and backward voltage is about 3.0V." The term backward voltage is confusing... is this forward voltage? Will this light up an LED? thank you, thomas

  • dbvanhorn / about 6 years ago * / 1

    I just bought one today, and having NO luck getting it to connect with my PC. Start gives me "open device failed". There's a dropdown for "unit" in the top center, but it is blank.

    No idea what's going on, but I bought it specifically to put a meter on a projector for classes. Hopefully someone from SF will chime in here, otherwise I will have to get something different.

    SOLVED!! Despite the instructions above, the software which is linked on this page is NOT the software that comes on the little orange CD with the meter. My laptop has no CD drive so I used the download link. BOTH versions of the software on the disk work with my meter. You have to manually try comports, but it does work.

    Otherwise the meter looks fine, but the ONLY reason I bought it isn't working. :(

  • Member #680432 / about 8 years ago / 1

    I just got this as a gift, and can't get the windows software to work. Must admit it's a bit annoying. However, it's still a nice multimeter.

  • bobdabiulder / about 8 years ago / 1

    Does this have min/max function?

  • Really? It clearly has an rs232 interface internally and a USB converter bolted on to cope with the current lack of serial ports on modern PCs but in 2015 a new product with closed USB drivers? Really?

    In 2015 it should be mandatory for a new design to not only have a standard USB interface but to have a published format for the data on the wire.

    And since you are supposed to be selling to people who tinker, how about expose the TTL serial interface on a header to allow it to interface to a microcontroller or your existing USB to TTL Serial interfaces?

    • dbc / about 9 years ago / 4

      When I saw it had a USB port, I thought: "Must Buy". Then I see it has some strange driver. Well, often these devices that are not badged "USB" use an FTDI chip or one of the other USB-to-serial converters, and then squat on some random VID/PID so that they don't have to pay the USB consortium to use the logo.

      So... I download the .rar file. And..... I find a Windows self-extracting .exe. So far in 2015, I have not had to boot Windows, and this isn't enough to motivate me. Maybe someone that buys one of these units can look at how it enumerates itself on the USB bus, and maybe try a CDCACM driver on it by associating the VID/PID. Or maybe some Windows user can poke around the same way.

      In any case, the temperature probe is nice in a meter in this price range. I had to pay out for a pretty spiffy Fluke in order to get a temperature probe.

      Wake me when the USB connectivity works on Linux or a Mac. I'd buy it instantly if I could interface data logging scripts to it.

      • Member #107599 / about 7 years ago / 1

        Wake me when the USB connectivity works on Linux or a Mac. I’d buy it instantly if I could interface data logging scripts to it.

        Wake up DBC! Sigrok appears to support it as driver-type uni-t-ut61c-ser

  • Member #483902 / about 9 years ago * / 2

    If you want to use windows, here is a vbscript to get the data from the unit: (baud rate is 2400, and com port is whatever it is on your machine, maybe COM3, who knows.. check device manager and change that part of the script..) Also for the drivers, you can get them from here for Windows 7 64 bit (the CD included doesnt have the win7 64 support):

    Save it as "ser.vbs"


    Set fso = CreateObject("Scripting.FileSystemObject")

    Set comObj = fso.OpenTextFile("COM5:2400,N,8,1", ForReading)

    if not comObj.AtEndOfStream then

    Wscript.Echo comObj.ReadLine

    end if


    Then execute that from windows command line like this:

    cscript /nologo ser.vbs

    You'll get values like: -0271 41

    The "-0271 41" result implies: -027.1 mV. The 41 refers to the digits shown and where the decimal place goes -- 4 digits and the 1 it looks like refers to mV. If the 1 is not shown, then it means volts.

    For example:

    "+0151 1", means 0.151 volts

    "+0151 2", means 01.51 volts

    "+0151 4", means 015.1 volts

    "+0151 0", means 0151 volts

    Explanation: 0 (no decimal), 1 (3 decimals), 2 (2 decimals), and 4 (1 decimal).

    • Member #483902 / about 9 years ago / 2

      I noticed also that if you can't get it to work with the vbscript from windows 7 when you first connect (it just hangs), then run this command. (assuming COM8)

      powershell "$port=new-Object System.IO.Ports.SerialPort COM8,2400,None,8,one; $port.Open();$port.Close();"

      It will connect to COM8 and then disconnect. For some reason that clears up the com port and is open and ready for talking to the vbscript.

  • bk0y / about 9 years ago / 2

    The google machine gave the following link as the first result when searching for "Victor 70C": link Note the very stylish color scheme on the Chinese version...

  • Member #562416 / about 9 years ago / 2

    232? Really?

  • Member #693354 / about 9 years ago / 1

    Have the Mac users succeeded using this Multimeter? Member #686974, have you gotten any "sensible data out of it" yet?

    • Member #483902 / about 9 years ago / 2

      Here is a python script to use it on mac osx and run from command line:

      Name it ""

      import serial

      ser=serial.Serial('/dev/tty.SLAB_USBtoUART', 2400, timeout=1)

      print ser.readline()

      You'll need to install pip and pyserial most likely:

      sudo easy_install pip

      sudo pip install pyserial

      Then run:


      You'll get data like this:

      +0000 4?

      See my other answer above about the explanation of the digits.

  • Member #686974 / about 9 years ago / 1

    On my mac it showed up as a cp2102 and if I install the usb serial driver from Silabs if shows up as a serial port is this a new version of the device? I was expecting a HID device. I will let you know if I can get sensible data out of it.

  • Member #685389 / about 9 years ago / 1

    If it is not OS agnostic, the so-called "USB" port is useless to me. E-mail me when it is a "real" USB port. Otherwise I think it would be a valuable instrument.

    • Member #107599 / about 7 years ago / 1

      It's an integrated USB<->Serial adapter. You can use sigrok.

  • Member #149561 / about 9 years ago / 1

    Is there a MAC driver available yet?

  • greggler / about 9 years ago / 1

    could anyone confirm if this information and linux solution for the victor70c also applies to this meter?


    • Member #107599 / about 7 years ago / 2

      Not quite. It turns out Victor_protocol is a scrambled version of FS9922. This device speaks straight FS9922, and can be interfaced with SigRok via driver-type uni-t-ut61c-ser

  • BradLevy / about 9 years ago / 1

    I'd also like to know: Are the AC measurements RMS? and Is the USB electrically isolated? If not, you could run into problems quickly measuring circuits connected to an AC line.


  • Member #371067 / about 9 years ago / 1

    Could someone verify the DC and AC current ranges, the above is not quite the same as the USER MANUAL, thank you

  • Member #39181 / about 9 years ago / 1

    What is the resolution? Reading the manual, I get the impression that this is 3 3/4 digits. Is that correct?

Customer Reviews

4.2 out of 5

Based on 6 ratings:

Currently viewing all customer reviews.

2 of 2 found this helpful:

A great addition to my bench

After 30 years in my career as an Electronics CET, I have twisted many Knobs, POT's and function switches sometimes ending up in the wrong range, wrong measurement function, flopping my DMM on it's side or collapsing it. The push button and auto range is a welcome relief. The RS232 commo is outstanding for logging data and also setting up a trouble shooting routine for equipment that is serviced continuously. This routine may be used by laymen in order to relieve the work load of the Supervising Technician. You can find great innovations, education and great products at Sparkfun! Thanks Guys

5 of 5 found this helpful:

Pretty good multimeter but RS232 output is a pain

This appears to actually be a Victor 70C multimeter, potentially with customized firmware. The included RS232 interface software is windows only but neither it nor open-source alternatives like sigrok-cli actually worked for me (Win7/64bit), though the DMM did register as a serial port.

For someone digging further into this, the the protocol is potentially documented at

Excellent device!

Not much else to say here except that this device is very excellent. It lives up to the expectation of a medium cost hobby meter and the autoranging feature is very stable. Definitely a tool to recommend.

Wanted to upgrade from analog to digital

This meter was affordable and digital. I looked at the yellow ones but could not justify the expense for a hobby. This has beeper for continuity checks and digital for other measurements. Works well for me.

Decent meter, esp for price

Looks like they took the Victor86C USB protocol and changed 1 or 2 things.

0 - jodenxunickxia is still the magic value for subtracting bytes 1 - I think the 'scrambler' step may have been reversed or else I'm reading the disassembly wrong. 2 - the bytes in the 14-byte packet are now bit-reversed.

Took some time to figure out how to make it work on Wiondows 10. Supplied drivers did not work for me. The latest version of sigrok-cli did the job. The following command line does the job: "sigrok-cli --driver uni-t-ut61c-ser:conn=COM4 --continuous". Make sure that RS232 is enabled on the device itself (Press and hold REL/RS232 button). COM4 above is the port USB port is mapped to. Look for Silicon Labs CP210x USB to UART Bridge in the Device Manager.