Voltcraft VC-870

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Voltcraft VC-870
Voltcraft vc870 mugshot.png
Status supported
Source code serial-dmm
Counts 40000
IEC 61010-1 CAT III (1000V) / CAT IV (600V)
Connectivity RS232 / USB
Measurements voltage, resistance, diode, continuity, capacitance, frequency, current, temperature, loop current, power + apparent power, power factor + frequency, effective voltage + current
Features autorange, hold, relative, backlight, min, max, minmax, true-rms, bargraph
Website conrad.de

The Voltcraft VC-870 is a 40000 counts, CAT III (1000V) / CAT IV (600V) handheld digital multimeter with RS232 or USB connectivity.

Hardware

Multimeter:

We don't have teardown photos yet, but this article (see also this photo) claims that the DMM contains the following components:

RS232 cable:

USB cable:

Photos

Multimeter:

RS232 cable:

See Device cables#UNI-T_UT-D02.

USB cable:

See Device cables#UNI-T_UT-D04.

Protocol

Some (partially incorrect and also incomplete) protocol docs are available from the vendor.

The interface parameters for the UNI-T UT-D02 serial cable are 9600/8n1.

A packet consists of 23 bytes:

Byte(s) Name Description
0 Function code Bytes 0 and 1 determine the measurement mode.
1 Function select code Bytes 0 and 1 determine the measurement mode.
2 Range
3-7 5 main display digits
8-12 5 auxiliary display digits
13 ?
14 ?
15 Status
16 Option 1
17 Option 2
18 Option 3
19 Option 4
20 Dual display
21 Line feed Always 10 / 0x0a.
22 Carriage return Always 13 / 0x0d.

Measurement modes:

Function code Function select code Measurement mode
0x30 0x30 DCV
0x30 0x31 ACV
0x31 0x30 DCmV
0x31 0x31 Temperature (Celsius and Fahrenheit)
0x32 0x30 Resistance
0x32 0x31 Continuity
0x33 0x30 Capacitance
0x34 0x30 Diode
0x35 0x30 Frequency
0x35 0x31 Loop current, (4-20mA)%
0x36 0x30 DCuA
0x36 0x31 ACuA
0x37 0x30 DCmA
0x37 0x31 ACmA
0x38 0x30 DCA
0x38 0x31 ACA
0x39 0x30 Active/real power + apparent power
0x39 0x31 Power factor + frequency
0x39 0x32 Voltage effective value + current effective value

Notes:

  • The bargraph value (only shown on the LCD for voltage, current, and resistance mode) is not contained in the protocol.
  • The auto-poweroff feature which powers the device off after 15 minutes is always disabled when the PC interface is "active" (i.e. the user pressed the REL/PC button for 1 second). Thus the respective "auto-poweroff" bit/flag, which is contained in the protocol, always has the same value.
  • The backlight status (on/off) is contained in the protocol.

Resources