Delta DVP-SS2

4. Communications
4-3
Default communication settings for all COM ports:
− Modbus ASCII
− 7 data bits
− 1 stop bit
− Odd parity
− Baud rate: 9600
4.2 Communication Protocol ASCII mode
Communication Data Structure
9600 (Baud rate), 7 (data bits), Even (Parity), 1 (Start bit), 1 (Stop bit)
Field name
Content
Explanation
Start bit
STX
Start bit ‘:’ (3AH)
Communication
address
ADR 1
Address consists of 2 ASCII codes
ADR 0
Command code
CMD 1
Command code consists of 2 ASCII
codes
CMD 0
Data
DATA (0)
Data content consist of 2n ASCII codes,
n≤205
DATA (1)
……….
DATA (n-1)
LRC checksum
LRC CHK 1
LRC checksum consists of 2 ASCII codes
LRC CHK 0
Stop bit
END1
Stop bit consists of 2 ASCII codes
END1 = CR (0DH),
END0 = LF (0AH)
END0
Corresponding table for Hexadecimal value and ASCII codes
ASCII
“0“
“1“
“2“
“3“
“4“
“5“
“6“
“7“
Hex
30H
31H
32H
33H
34H
35H
36H
37H
ASCII
“8“
“9“
“A“
“B“
“C“
“D“
“E“
“F“
Hex
38H
39H
41H
42H
43H
44H
45H
46H
4.2.1 ADR (Communication Address)
Valid communication addresses are in the range of 0~254. Communication address equals to 0 means
broadcast to all PLCs. PLC will not respond to a broadcast message. PLC will reply a normal message
to the master device when communication address is not 0.
Example, ASCII codes for communication address 16 in Decimal. (16 in Decimal = 10 in Hex)
(ADR 1, ADR 0)=’1’,’0’’1’=31H, ‘0’ = 30H