JSON Protocol

Packet Format

All packets specified in this protocol adopt the standard TLV (Type, Length, Value) format, including a fixed start header and CRC checksum.

Item	Length (Byte)	Description
SyncByte	2	Fixed header 0x4E66
Length	2	Hex length 0~2000; excludes header, command word, and CRC segments
Command	2	Command word
data	Length	Data segment (primarily JSON format)
CRC	4	CRC32 checksum over all data excluding the header

The data segment is primarily in JSON data format.

Example

To set Robot 1 servo status to 0, send the following data (hexadecimal):

4e 66 00 17 20 01 7b 22 72 6f 62 6f 74 22 3a 31 2c 22 73 74 61 74 75 73 22 3a 30 7d 0a 6b 92 6d ff

Data segment breakdown:

Field	Content
4e 66	Fixed header
00 17	Data segment length (23 bytes)
20 01	Command word
7b...7d 0a	Data segment, corresponds to ASCII string {"robot":1,"status":0}\n (0x0a is newline, optional)
6b 92 6d ff	CRC32 checksum

Data segment ASCII mapping:

7b  -->  {
22  -->  "
72  -->  r
6f  -->  o
62  -->  b
6f  -->  o
74  -->  t
22  -->  "
3a  -->  :
31  -->  1
2c  -->  ,
22  -->  "
73  -->  s
74  -->  t
61  -->  a
74  -->  t
75  -->  u
73  -->  s
22  -->  "
3a  -->  :
30  -->  0
7d  -->  }
0a  -->  newline (optional)

If the final 0x0a newline is omitted, the transmitted data becomes:

4e 66 00 16 20 01 7b 22 72 6f 62 6f 74 22 3a 31 2c 22 73 74 61 74 75 73 22 3a 30 7d 53 dd eb 72

Controller Ports

Port	Protocol	Usage
5000	TCP	Transfer import/export job files, configuration files, software upgrades; large job file transfers can also use FTP
6000	TCP	Regular command transmission, primarily for teach pendant and other program development
7000	TCP/UDP	Receive status broadcast information, no heartbeat mechanism required

Heartbeat Mechanism

After establishing a 5000/6000 communication port connection, a heartbeat mechanism must be designed to ensure the communication status remains normal.

Process:

1. The teach pendant periodically sends heartbeat check packets to the controller
2. Upon receiving the heartbeat packet, the controller replies with a heartbeat response packet containing the timestamp carried in the check packet
3. The teach pendant checks whether the data in the response packet is correct
4. If the data is incorrect or a timeout occurs without receiving a response, the connection is considered potentially interrupted

Heartbeat Timeout: 6 seconds