Communication Protocol - Chroma 19071 User Manual

5.4

Communication Protocol

This interface uses half duplex of 2-wire system non-synchronized transmission mode.
Master
Slave 1
Before the bus control is transferred, please wait the time of two characters.
Master
n1 Bytes
The transmission format of character is 1 initial bit, 8 data bits and 1 end bit, the total is 10
bits.
START 0
The receivers don't respond any data under broadcast mode. When the receivers receive
the query functions under node-to-node transmission mode, it returns the relative data.
However, the receivers receive the execution command, it returns the result of executing.
About Reply Message, please refer the descriptions of command.
The commands are packed into packets, Data Frame as the following:
Header DA
1 byte 1 byte
Header:
Destination Address:
Source Address:
Data Field Length:
Data Field:
Command Code
1 byte
Checksum: Summing these values into two's complements, included data are DA + SA +
Length + Data Field
RS485 Interface (For Link Model of 19073 + RS485)
Slave n
Slave1
2 Bytes n2 Bytes
1 2 3
SA Length
1 byte 1 byte
0xAB
0x0 ~ 0x7F, 0xFF is broadcast address
0x0 ~ 0x7F
It means the length of data field.
Please refer the command set.
Parameter
0 ~ n-1 bytes
Master
2 Bytes n3 Bytes
4 5 6
Data Field Checksum
n bytes 1 byte
Slave n
2 Bytes n4 Bytes
7 STOP
5-3