Mitsubishi MELSEC LJ71C24, Руководство пользователя

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App. - 54 App. - 54
APPENDIXES
(5) Calculating range of Check code
The following shows specification examples of the calculating range of Check
code.
Packet
element 1
Header Static data
Calculating range when specifying 1 to (n-1)
Example 1
Packet
format
Example 2
Example 3
Calculating range when specifying 2 to (n-1)
Calculating range when specifying 2 to (n-2)
Terminator
Non-conversion
variable
Check code
Packet
element 2 Packet
element n-2 Packet
element n-1 Packet
element n
Example 1: Calculating range when its start is 1 and end is n-1.
Example 2: Calculating range when its start is 2 and end is n-1.
Example 3: Calculating range when its start is 2 and end is n-2.
Appendix 5.3.5 Non-verified reception
The following shows a usage example of Non-verified reception.
1 byte
STX
Header Non-verified reception (variable number of characters) Terminator
Conversion
variable
Data needed by the user
Set a Non-verified
reception element
When the data are not needed by
the user and data contents and/or
the number of character vary
Identification
code
Country
code
Manufacturer
code
Product code ETX
2 bytes
1 byte 2 bytes
2 bytes 5 bytes
Data
to be read
5 bytes 1 byte
1 byte
Variable
number of
characters
Variable
number of
characters
Example of format of packet from other device
Example of packet setting
Using a Non-verified reception element has the following advantages in the case of the
packet format shown above.
y The only necessary data can be stored in the device memory of a CPU module and
buffer memory.
y A single protocol (packet) can handle receive packets that includes data whose
contents vary each time.