Voltcraft VC-350e

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Voltcraft VC-350e
Voltcraft VC-350e.jpeg
Status not supported
Counts 4000
IEC 61010-1 CAT II (750 V AC/1000 V DC)
Connectivity RS-232 (Metex)
Measurements voltage, current, resistance, diode, continuity, temperature, frequency
Features autorange, hold, bargraph

The Voltcraft VC-350e is a 4000 counts, CAT II (750/1000V) handheld digital multimeter with RS232 connectivity.

It is an OEM version of the Saftec SAF350E. The device was sold by Conrad Elektronik as article 125512 around 1997 and is not available any more.

Hardware

Multimeter:

  • Multimeter IC: Maxim MAX134 datasheet
  • CPU: SAF350E (can be found under the LCD, markings on chip: 941d saftec saf 350-98)
  • Fuses: 800mA/250V 5x20mm and 20A/250V 6x30mm (superfast, ceramic fuses)
  • Battery: 9V NEDA 1604 or 6F22


RS-232 pinout and connection settings

  • Transfer rate:1200 baud
  • Characters: 8-bit
  • Parity:none
  • Stop bits:1

This device uses what looks like a Metex connector, but it only has 4 pins (where 5 pins is seen on other devices).

Vc350e-rs232.png

Metex-connector pin RS-232 DE9-female pin Signal (multimeter side) Remarks
1  3 RxD
-  - empty space space between pin 1 and 2 on Metex where there is no pin/hole.
2  5 GND
3  2 TxD  
4  6, 7 DSR + RTS  DSR and RTS tied together on PC side

Serial protocol

To test on a Linux computer using the screen command, open a terminal like xfce4-terminal, gnome-terminal or xterm and start a session, we will use this terminal to display the data coming from the multimeter:

/usr/bin/screen -d -m -S serial /dev/ttyUSB0 1200
screen -r serial

Then open a new terminal to send commands to the multimeter, example to read the current measurements:

screen -S serial -X stuff "$(echo -e '\xE0\xFF\r')"

Output something like "012.003 V". Often the units show garbled, aka you will see "012.003 �" or something especially when using Ohms. I remember I also had this with the original vendor software (which I no longer have). So maybe my device is poor or it was just never developed better.

Taken from the manual found at elektroda.pl.

The following commands can be send over RS-232:

C0 Yellow
C1 Relative
C3 Blue
C4 Record
C5 Range Hold
C6 Memory
C7 Recall
C8 AC Power Off
CA Power off timeout enable
CB Power off timeout disable
A0-A6 Manual range set
E0 Get measured value read out


All commands must be terminated by hexadecimal FF. Also multimeter will terminate it's response with hexadecimal FF.

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