User Manual

10
RTU Mode:
To Read Instruction
To Read Response
Message
To Write Instruction
To Write Response
Message
Machine address 01H 01H
Machine
address
01H
01H
Machine
address
01H
01H
Machine
address
01H
01H
Instruction 03H 01H Instruction 03H 01H Instruction 06H 05H Instruction 06H 05H
10H 08H 10H 08H 10H 08H
Starting address of
reading data
00H
10H
Response data
length (byte)
04H
02H
To write
data
address
01H
10H
To write data
address
01H
10H
00H 00H 01H 17H 03H FFH 03H FFH
To read data length
(word/bit)
02H
09H
Data content 1
F4H 01H
To write
data
content
20H
00H
To write data
content
20H
00H
CRC low byte
C0H
BBH 03H
CRC low
byte
DDH
8FH
CRC low byte
DDH 8FH
CRC high byte
CBH
A9H
Data content 2
20H
CRC high
byte
E2H
9FH
CRC high byte
E2H 9FH
CRC low byte BBH 77H
CRC high byte 15H 88H
CRC (Cyclical Redundancy Check) program example:
unsigned int reg_crc = 0xffff; i = 0;
while (length--)
{
reg_crc ^= RTUData[i];
i ++;
for (j = 0; j < 8; j++)
{
if (reg_crc & 0x01) reg_crc = (reg_crc >> 1) ^ 0xA001;
else reg_crc = reg_crc >> 1;
}
}
return (reg_crc);
11 INSTALLATION
SCD series can be extended up to 8 modules and installed by DIN rail mounting.
1
2
SCD unit
Mounting Panel
DIN rail
1
2
3
12 HOW TO SET UP CURRENT INPUT
For normal input For current input (4 ~ 20mA, 0 ~ 20mA)
JUMPER
PIN HEADER
JP1
DEFAULT SETTING
JUMPER
PIN HEADER
JP1