OTA (Over-The-Air) Packet

Field	Size (bits)	Bit Range	Description	Breakdown
Header
Start byte	8	0–7	Starting character $ (ASCII value 36)	$
Data length	12	8–18	2-byte length of the data following the header	—
Num of data packets	5	19–23	Number of packets (0–32)	0 - 32
IMEI	50	24–74	Unique device identifier	Integer type: e.g., 887744556677882
Packet Type	5	75–79	Type of packet	00 - Device info 01 - Alert packet 02 - OTA pkt 03 - Error Packet 04 - Device configuration packet 05 - IP configuration packet
Data
OTA Source	5	—	Source of OTA	00 - OTA_SRC_SERIAL 01 - OTA_SRC_SMS 02 - OTA_SRC_IP_TRANSIGHT 03 - OTA_SRC_IP_CUSTOMER
Error status	8	—	Non-zero value indicates an error	0 = No Error, Non-zero = Error
Cell Number	51	—	First bit (MSB) indicates presence of country code. Remaining 50 bits = mobile number	Example: 400D6276ACF52 (+919784312658)
Date & Time	32	—	UTC Timestamp	UTC time in seconds
Timezone	8	—	Timezone in quarter-hours (e.g., 22 = +5:30)	22 × 15 mins = 330 mins = +5:30
Command Length	8	—	Length of command string	—
Command	up to 600 bits (75 bytes)	—	Command with arguments, null-terminated string	Example: SET CUIOCFG:IO1-DI-IGNIO2_AN_GENIO3-DI-PBNIO4-DO-IMB
Response Length	8	—	Length of response string	—
Response	up to 512 bits (64 bytes)	—	Response string from device	Example: IOCFG:IO1-DI-IGNIO2-AN_GENIO3-DI-PBNIO4-DO-IMB
Tail
End Character	8	0–7	End character * (ASCII value 42)	*
CRC	8	8–15	8-bit XOR CRC from $ to * (excluding both)	—

Sample Packet

 {"HEX:240340e1cabd09208ca210000000000000006824646f160947455420545355524c1c55524c3a5443503a3134312e3134372e3132382e3135303a383738382aa2",
  "cell_no": 0,
  "command": "GET TSURL",
  "command_length": 9,
  "dateTime": 1747215471,
  "dateTime_tz": "2025-05-14 15:07:51.000",
  "error_status": 0,
  "imei": 860187062240357,
  "insert_time": "Wed, 14 May 2025 09:38:03 GMT",
  "ota_source": 2,
  "packetType": 2,
  "response": "URL:TCP:141.147.128.150:8788",
  "response_length": 28,
  "send_time": "2025-05-14 15:07:51",
  "timezone": 22}