Voltcraft VC-820
The Voltcraft VC-820 is a 4000 counts, CAT III (1000V) / CAT IV (600V) handheld digital multimeter with RS232 or USB connectivity.
Hardware
Multimeter:
- Fortune Semiconductor FS9721_LP3
- 4MHz crystal
- Fuses: 10A/250V and 500mA/250V (glass fuses)
RS232 cable:
USB cable:
Photos
Multimeter:
Device, front
Device, back
Device, back w/o battery
Battery 1
Battery 2
Device, open
Device, open 2
Cover 1
Cover 2
Shielding
IR assembly
IR PCB, top
IR PCB, bottom
PCB, front
PCB, back
PCB, top
PCB, light 1
PCB, light 2
FS9721_LP3
Crystal
LCD, front
LCD, back
LCD, all segments
RS232 cable:
See Multimeter cables#UNI-T_UT-D01.
USB cable:
See Multimeter cables#UNI-T_UT-D04.
Protocol
The connection to the PC is done using a cable which converts the optical signal (IR) on the multimeter to RS232.
The serial connection uses 2400 baud (hardcoded, cannot be changed) with 8n1 settings. The multimeter transmits 14-byte data packets periodically, the host can not send any commands whatsoever, only read the transmitted data.
A short protocol description is available from Voltcraft/Conrad.