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| HaierProtocol | ||
| ============= | ||
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| This library implements a Haier protocol transport level. It can help | ||
| with sending and receiving messages to appliances that support it and | ||
| process answers. | ||
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| Protocol description | ||
| -------------------- | ||
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| Haier protocol is a synchronous protocol. All data delivered with this | ||
| protocol is split into portions - frames. The protocol has two versions. | ||
| One is used for older HVAC units that work with the SmartAir2 | ||
| application. Another is for newer units that work with the hOn | ||
| application. Those version commands are different but the frame | ||
| structure and transport level of the protocol are the same. | ||
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| Haier frame | ||
| ----------- | ||
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| .. list-table:: Frame structure | ||
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| * - **Frame separator** | ||
| - **Frame length** | ||
| - **Frame flags** | ||
| - **Reserved space** | ||
| - **Type** | ||
| - **Frame data** | ||
| - **Checksum** | ||
| - **CRC** | ||
| * - 2 bytes | ||
| - 1 byte | ||
| - 1 byte | ||
| - 5 bytes | ||
| - 1 byte | ||
| - | n bytes | ||
| | (n <= 246) | ||
| - 1 byte | ||
| - 2 bytes | ||
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| Where: | ||
| * **Frame separator** - 2 bytes, have fixed value 0xFF 0xFF, used as a marker for the beginning of the frame | ||
| * **Frame length** - 1 byte, number of bytes of the entire frame, includes frame flags, reserved space, type byte, frame data, and checksum, max value is 254 \* | ||
| * **Frame flags** - 1 byte, only 2 values used 0x40 - indicates that frame have CRC bytes, 0x00 - indicates that there is no CRC | ||
| * **Reserved space** - 5 bytes, reserved for future use, filled with 0x00 | ||
| * **Frame type** - 1 byte, type of frame (depend on the protocol) | ||
| * **Frame data** - n byte, data of the frame, can be empty. Sometimes first 2 bytes of data are used as a subcommand. Max size 246 | ||
| * **Checksum** - 1 byte, the least significant byte of the sum of all bytes of the frame except separator bytes, CRC, and checksum itself. | ||
| * **CRC** - 2 bytes, CRC 16 of all bytes of the frame except separator bytes and CRC itself (Modbus CRC algorithm used). CRC is available only if the frame flags byte indicates it. |