V&A VA18B

Mastech VA18B

The Mastech VA18B a.k.a. V&A VA18B (V&A is a brand of Mastech) is a CAT II (1000V) handheld digital multimeter with USB connectivity.

See Mastech VA18B/Info for more details (such as lsusb -vvv output) about the device.

Model overview

There seems to have been at least two different revisions of the multimeter (or at least of the PC-Link cable). The older one used a Sunplus SPCP825 USB-to-serial chip (see [1], also the software from here), the newer revisions use a Prolific PL2303 chip.

Rebranding of Mastech multimeters in this series:

• Velleman DVM1000 (no PC connectivity)
• Velleman DVM1100 (no PC connectivity)
• Velleman DVM1200 (USB), rebranded Mastech VA17B (run "strings" on some software files)
• Velleman DVM1400 (no PC connectivity)

Hardware

Multimeter:

• ...

USB cable:

• Prolific PL2303HX YR0903A
• 12MHz crystal

Photos

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  Device, front

• 

  PCB, front

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  PCB, back

• 

  USB cable

• 

  USB cable PCB, front

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  USB cable PCB, back

Protocol

14-byte LCD segments over USB-2-serial (Prolific PL2303 chip, 2400 baud, 8n1), see various links below.

To enable output to the PC on the multimeter you have to keep the "Hz/DUTY" key pressed while powering on the device.

Resources

• Protocol descriptions: [2], [3], [4]
• EEVblog forums: Product review: DMM latest V&A Mastech VA18B