Race666/Metex-M3850D

Repository for projects regarding my Metex/Voltcraft M3850D

Metex / Voltcraft Projects

Project 1: A simple powershell library to read values from the multimeter

Usage of the library: Source the library

. .\libmetex.ps1

Create a new instance

$Metex=new-object MetexM3850D("COM5")

Open the COM Port

$Metex.Open()

Read Measures

$Metex.ReadMeasureSynchron()
$MeasureResult=$Metex.ReadMeasureSynchron()

Output should be something like this

MeasuringUnit    : Diode
Value            : 0
RawMeasureString : DI    OL   mV
Result           : Overload
Unit             : V
RawValue         : OL
RawUnit          : mV

MeasuringUnit    : Capacity
Value            : 4E-12
RawMeasureString : CA  0.004  nF
Result           : OK
Unit             : F
RawValue         : 0.004
RawUnit          : nF

MeasuringUnit    : CurrentDC
Value            : -1E-07
RawMeasureString : DC -000.1  uA
Result           : OK
Unit             : A
RawValue         : -000.1
RawUnit          : uA

Close the COM Port

$Metex.Close()

Project 2: An adapter to connect a multimeter by a UART to USB Converter (CB2102) to a PC

The Kicad project is a simple converte to connect a M3850D by a TTL UART to USB Converter to PC.

The Description of the Serial port pins of the Multimeter:

RxD and TxD Ports are MAX232 compatible. Means -12V = High and +12V is Low Level.

Therefore the ports must be inverted (done by Transistor Q1) to deal with a TTL USB adapter. This is only necessary for RxD because to start a measurement read, only a falling rise at TxD port is requiered, indepentend which character is send to the multimeter.

The multimeter serial port is isolated by optocouplers from the multimeter. A supply voltage is needed.

DTR and RTS Ports are just used for the power supply of the optocouplers not for a serial handshake.

In my test a 5V supply is sufficent. RTS=GND DTR=5V

This is the schmetic: