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Protocol of the Lacrosse TX3-TH thermo/hygro sensorCompatible: TX4, et certainly others... |
Each frame is 44 bits long. It is composed of:
- 1 bloc of four bits = 0 (start sequence) [blue]
- 9 blocks of four bits (data)
- 1 block of four bits (checksum) [red]
Example 1
| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 1 |
Example 2
| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 |
Example 3
| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 |
Example 4
| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 |
The active values of the frames are explained below:
- Length of data [white]
- Type of measure (0=Thermo E=hygro) [yellow]
- Address of sensor [cyan]
- Unknown bit [purple]
- Measure [green]
- Checksum (Lower four bits of the sum of all words excluding header and length) [red]
Example 1
| 1 | 0 | 1 | 0 | | 0 | 0 | 0 | 0 | | 0 | 0 | 0 | 0 | | 1 | 1 | 1 | 0 | | 0 | 1 | 1 | 1 | | 0 | 0 | 1 | 1 | | 0 | 0 | 0 | 1 | | 0 | 1 | 1 | 1 | | 0 | 0 | 1 | 1 | | 1 | 1 | 0 | 1 |
| A | | 0 | | 0 | | 7 | 0 | | 7 | | 3 | | 1 | | 7 | | 3 | | D | |
| Checksum: (A + 0 + 0 + E + 7 + 3 + 1 + 7 + 3) and F = D | | D |
Example 2
| 1 | 0 | 1 | 0 | | 1 | 1 | 1 | 0 | | 1 | 1 | 0 | 0 | | 1 | 1 | 0 | 0 | | 0 | 1 | 1 | 0 | | 0 | 0 | 0 | 0 | | 0 | 0 | 0 | 0 | | 0 | 1 | 1 | 0 | | 0 | 0 | 0 | 0 | | 1 | 1 | 0 | 0 |
| A | | E | | C | | 6 | 0 | | 6 | | 0 | | 0 | | 6 | | 0 | | C | |
| Checksum: (A + E + C + C + 6 + 0 + 0 + 6 + 0) and F = C | | C |
Example 3
| 1 | 0 | 1 | 0 | | 0 | 0 | 0 | 0 | | 0 | 1 | 0 | 0 | | 0 | 1 | 0 | 0 | | 0 | 1 | 1 | 1 | | 0 | 0 | 1 | 0 | | 0 | 0 | 1 | 1 | | 0 | 1 | 1 | 1 | | 0 | 0 | 1 | 0 | | 0 | 1 | 1 | 1 |
| A | | 0 | | 4 | | 2 | 0 | | 7 | | 2 | | 3 | | 7 | | 2 | | 7 | |
| Checksum: (A + 0 + 4 + 4 + 7 + 2 + 3 + 7 + 2) and F = 7 | | 7 |
Example 4
| 1 | 0 | 1 | 0 | | 1 | 1 | 1 | 0 | | 0 | 0 | 0 | 0 | | 1 | 1 | 1 | 1 | | 0 | 1 | 0 | 1 | | 0 | 0 | 1 | 0 | | 0 | 0 | 0 | 0 | | 0 | 1 | 0 | 1 | | 0 | 0 | 1 | 0 | | 0 | 1 | 0 | 1 |
| A | | E | | 0 | | 7 | 1 | | 5 | | 2 | | 0 | | 5 | | 2 | | 5 | |
| Checksum: (A + E + 0 + F + 5 + 2 + 0 + 5 + 2) and F = 5 | | 5 |
| | Sensor type |
| | Sensor Address |
| | Data values |
| | Checksum |
The measure is on 3 BCD digits, the two first digits are repeated to fill the 5 nibles.
For temperature, an offset of 50 deg has to be substracted from the measure.
- [tempe] 23.1 deg
- [hygro] 60.0 %
- [tempe] 22.3 deg
- [hygro] 52.0 %
I did not find the meaning of the purple bit.
I am interested by any comment or more information on the format of these frames. Contact: Jean-Paul ROUBELAT - F6FBB
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