Mitsubishi FX3U-USB-BD User Manual page 545

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
8.2.6 Sum check code
The sum check code indicates a two-digit ASCII code converted from the lowest-order byte (8-bit) of the
result (sum) acquired by adding the sum check target data as hexadecimal data.
By setting a parameter, set whether or not the sum check code is added in the message.
• When "sum check provided" is selected, the sum check code is added in the message during sending.
During receiving, the sum check code is compared with the value calculated from the received data to
check the received data.
• When "sum check not provided" is selected, the sum check code is not added, so the received data is not
checked either.
A calculation example of the sum check code is shown below.
Example: When the communication format (parameters) is set as follows
- Control line not provided
- Headers provided [DLE+STX (D8410: 0210H, D8411: 0000H)]
- Terminators provided [DLE+ETX (D8412: 0310H, D8413: 0000H)]
In the case of send data
Send data
In the case of receive data
Receive data
Header Data area
DLE STX 31H 32H
D8410 D8410 D100 D100
lowest highest lowest highest lowest
-order -order -order -order
byte byte byte byte
Sum check code target
D100 lowest-order bits
D100 highest-order byte → 32H
D101 lowest-order byte
D101 highest-order byte → 34H
D8412 lowest-order byte → 10H (DLE)
D8412 highest-order byte → 03H (ETX)
Header Data area
DLE STX 35H 36H
D8410 D8410 D200 D200
lowest highest lowest highest lowest
-order -order -order -order -order
byte byte byte byte
Sum check code target
D200 lowest-order bits
D200 highest-order byte → 36H
D201 lowest-order byte → 37H
D201 highest-order byte → 38H
D202 lowest-order byte → 10H
D202 highest-order byte → 03H
8 Creating Programs (RS2 Instruction)
Terminator
33H 34H DLE ETX
D101 D101 D8412 D8412
highest
highest lowest highest
-order
-order -order -order -order
byte byte byte byte
→ 31H
→ 33H
DDH
Terminator
37H 38H DLE ETX
D201 D201 D202 D202 D8414
highest
highest lowest highest
-order
-order -order -order
byte byte byte byte
→ 35H
EDH
Converted into ASCII codes
8.2 How to Use RS2 Instruction
The order is
Sum data . . . . .
different from
the data area.
44H 44H
Sum Sum
CR LF
lowest
-order
byte byte
Converted into ASCII codes
The order is
Sum data . . . . .
different from
the data area.
45H 44H
Sum Sum
D8414
CR LF
lowest
-order
byte byte
Compared
4544H
A
B
C
D
E
F
G
H
I
Apx.
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