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Serial

  • Payload encoding: UTF-8
  • Request body inside serial payload is form-encoded key/value pairs

Serial frame format​

+------+-------------------+---------------------+------+
| STX  | Payload (N bytes) | CRC32 (4 bytes, BE) | ETX  |
| 0x02 | UTF-8 text        | over payload only   | 0x03 |
+------+-------------------+---------------------+------+

Rules:

  • CRC algorithm: CRC32.
  • CRC byte order in frame: big-endian.
  • CRC input: payload bytes only.
  • After CRC is calculated, any CRC byte equal to 0x03 is replaced with 0x20.
  • Invalid frame or CRC mismatch must be treated as invalid request/response frame.

Serial payload format​

Form-encoded fields:

  • command (required): route, for example /sale or sale
  • data (required): Base64 of UTF-8 JSON business payload
  • sign (required): signature string

Example payload string:

command=/check_status&data=eyJkb2N1bWVudEV4dElEIjoiT1JERVItMTAwMSJ9&sign=<SIGN>