TekPower TP4000ZC
The TekPower TP4000ZC is a 4000 counts handheld digital multimeter with RS232 connectivity.
Hardware
This multimeter appears to be a rebadged Digitek DT4000ZC.
- The microcontroller is an unidentifiable plastic blob.
- LM359 opamp
- HEF4013BT flip-flop
The RS-232 connector is a standard 3.5m stereo jack, with the ring left unconnected. The transmitter is optically insulated from the rest of the device The DB-9 connector has a loopback resistor between the RX and TX pins.
Photos
Device, angle
Mugshot
Device, back
Package contents
Holster removed, front
Holster removed, back
Battery compartment
Rear cover
Front cover
Front cover, PCB removed
PCB, front
PCB, back
Chip
HEF4013BT flip-flop
LM358 opamp
RS-232 optoisolation
RS-232 module
RS-232 PCB, bottom
RS-232 PCB, top
Supplied RS-232 cable
RS-232 cable, disassembled
RS-232 cable, detail
Protocol
The device periodically sends 14-byte packets at 2400 baud, 8n1. The MSB nibble of each byte indicates the byte number. The payload is composed of the LSB nibbles, and is a 1-1 mapping of the LCD segments.
Packet structure
| Byte | 7-4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|
| 0 | 0x1 | AC | DC | Auto | RS232 |
| 1 | 0x2 | Negative | 1A | 1B | 1C |
| 2 | 0x3 | 1D | 1E | 1F | 1G |
| 3 | 0x4 | DP1 | 2A | 2B | 2C |
| 4 | 0x5 | 2D | 2E | 2F | 2G |
| 5 | 0x6 | DP2 | 3A | 3B | 3C |
| 6 | 0x7 | 3D | 3E | 3F | 3G |
| 7 | 0x8 | DP3 | 4A | 4B | 4C |
| 8 | 0x9 | 4D | 4E | 4F | 4G |
| 9 | 0xa | u | n | k | Diode |
| 10 | 0xb | m | % | M | Beep |
| 11 | 0xc | Farads | Ohms | Rel | Hold |
| 12 | 0xd | A | V | Hz | Low battery |
| 13 | 0xe | hFE | Celsius | Reserved | Reserved |
Segment lettering
| C | ||
| B | G | |
| F | ||
| A | E | |
| D |