#2200087-Serial-Protocol
The 2200087 is an inexpensive DMM sold at radioshack. It supports logging and graphing data on a computer, but the supplied code only supports Windows. This is a python script to allow for connecting to the multimeter over USB on Linux or Mac OSX. Due to radioshack not supplying any serial specifications, the below protocol was reverse engineered from simply observing the output of the DMM.
#Installation and Usage
Start by cloning this repository:
git clone https://github.com/ddworken/2200087-Serial-Protocol.gitThen install dependencies:
pip install numpy pyserialThen you're ready to go. So just run the program:
sudo python serialDecoder.py -p /dev/ttyUSB0If you want a graph as your output, first install GNUPlot:
sudo apt-get install gnuplot
then run:
sudo python serialDecoder.py -p /dev/ttyUSB0 --graphYou also can read from multiple multimeters at the same time and get a CSV output like so:
sudo python serialDecoder.py -p /dev/ttyUSB0 /dev/ttyUSB1If you only want the actual values and not information about what mode the multimeter is on, use the -q flag:
sudo python serialDecoder.py -p /dev/ttyUSB0 -q#Protocol Description
| Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 | |
|---|---|---|---|---|---|---|---|---|
| Byte 1 | 0 | 0 | 0 | 1 | Minus | AC | SEND | AUTO |
| Byte 2 | 0 | 0 | 1 | 0 | Continuity | Diode | Low Batt | Hold |
| Byte 3 | 0 | 0 | 1 | 1 | MAX | E4 | F4 | A4 |
| Byte 4 | 0 | 1 | 0 | 0 | D4 | C4 | G4 | B4 |
| Byte 5 | 0 | 1 | 0 | 1 | DP3 | E3 | F3 | A3 |
| Byte 6 | 0 | 1 | 1 | 0 | D3 | C3 | G3 | B3 |
| Byte 7 | 0 | 1 | 1 | 1 | DP2 | E2 | F2 | A2 |
| Byte 8 | 1 | 0 | 0 | 0 | D2 | C2 | G2 | B2 |
| Byte 9 | 1 | 0 | 0 | 1 | DP1 | E1 | F1 | A1 |
| Byte 10 | 1 | 0 | 1 | 0 | D1 | C1 | G1 | B1 |
| Byte 11 | 1 | 0 | 1 | 1 | Percent | HFE | Rel Delta | MIN |
| Byte 12 | 1 | 1 | 0 | 0 | u (1e-6) | n (1e-9) | dBm | Seconds |
| Byte 13 | 1 | 1 | 1 | 1 | Farads | Amps | Volts | m (1e-3) |
| Byte 14 | 1 | 1 | 1 | 0 | Hz | Ohms | K (1e3) | M (1e6) |
All bytes are sent over in hexadecimal numbered one through fourteen. Bytes 3-4 contain digit 4, bytes 5-6 contain digit 3 and so on. All other parts of the display are turned on as shown in the above table.
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serialDecoder.py is a python program to decode the serial output from this DMM. Run:
sudo python serialDecoder.py -p /dev/ttyUSB0to display a text output of the data. Run:
sudo python serialDecoder.py -p /dev/ttyUSB0 graphto display a graph of the data.