Delta Electronics Programmable Logic Controller DVP-PLC - Manual (Page 422)

8 Application Instructions API 100-149
DVP-PLC Application Manual 8-20
M1002
X10
M1123
RST M1123
RS D100 K8 D120 K8
SET M1143
SET M1161
RTU Mode
8- bit Mode
Write transmitting data in advance
transmission
request
pulse
Receiving completed and flag reset
MOV D1120 H87
SET M1120
MOV D1129 K100
Set up communication protocol
to 9600, 8, E, 1
Retain communication protocol
Set up communication
time-out: 100ms
SET M1122 Set up transmission request
receiving completed
Process received data
PLC VFD-S, PLC sends: 01 06 2000 0012 02 07
Registers for sent data (sending messages)
Register DATA Explanation
D100 low 01 H Address
D101 low 06 H Function
D102 low 20 H
D103 low 00 H
Data address
D104 low 00 H
D105 low 12 H
Data content
D106 low 02 H CRC CHK 0
D107 low 07 H CRC CHK 1
The error checksum CRC CHK (0,1) can be calculated by CRC instruction (in 8-bit mode, M1161 = On).
M1000
CRC D100 K6 D106
CRC checksum: 02 H is stored in the lower 8 bits of D106 and 07 H in the lower 8 bits of D107,
Remarks:
1. The format of RTU mode with a communication datum
START Time interval
Address Communication address: 8-bit binary
Function Function code: 8-bit binary
DATA (n-1)
…….
DATA 0
Data content:
n × 8-bit data
CRC CHK Low
CRC CHK High
CRC checksum:
16-bit CRC checksum consists of 2 8-bit binaries
END Time interval
2. CRC checksum starts from Address and ends at Data content.