V&A VA40B
 | |
| Status | supported |
|---|---|
| Source code | serial-dmm |
| Counts | 6000 |
| IEC 61010-1 | CAT III (1000V) / CAT IV (600V) |
| Connectivity | USB/serial |
| Measurements | voltage, current, resistance, capacitance, frequency, temperature, duty cycle, diode, continuity |
| Features | autorange, data hold, relative, min/max, backlight |
| Website | mastech.com.cn |
The V&A VA40B is a 6000 count CAT III (1000V) / CAT IV (600V) handheld digital multimeter with USB connectivity.
See V&A VA40B/Info for more details (such as lsusb -v output) about the device.
Note: The company V&A ("SHANGHAI YIHUA V&A INSTRUMENT CO., LTD, known as Mastech Shanghai") has apparently been part of (or related to) MASTECH in the past, and also sells some multimeter models that have been sold by MASTECH in the past.1
The manufacturer name isn't stated anywhere on the device, package or manual. The Velleman DVM4100 model looks identical to the VA40B, except for its labels and blue case color, but their protocols differs. The VA40B also has some similarities with the V&A VA18B and the PeakTech 3415.
Hardware
Multimeter:
- Fuses: F 0.63A/1000V D10,3*38, F 10A/1000V D10,3*38 (values from the manual)
- TODO
USB cable:
Photos
Package, contents
Bag
Bag, open
Device, front
Device, back
Device, top
Device, front without bumper
Device, back without bumper
Device, display at power on
Probes
Thermocouple K type
Protocol
14-byte LCD segments over USB-to-serial (Prolific chip, 2400 baud, 8n1). The DMM IC used in this multimeter is probably a Fortune Semiconductor FS9721_LP3 or a Dream Tech International DTM0660 with protocol options set accordingly.
The manufacturer specific last byte of the 14-byte packet (numbered 0xe) is as follows:
| Byte | Bits 7-4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
|---|---|---|---|---|---|
| 13 | 0xe | MIN | (unused?) | °C | MAX |
To enable output to the PC on the multimeter you have to keep the Hz/DUTY key pressed while powering on the device. However, it will auto-poweroff (after roughly 1 hour?), even in this mode. To avoid that, press both the Hz/DUTY and the SELECT key during power-up (see manual page 19).