Mitsubishi MELSEC LJ71C24, Руководство пользователя

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9 DATA COMMUNICATION USING THE PREDEFINED PROTOCOL
9.3 Packet Elements
A packet consists of packet elements.
Up to 32 elements can be placed in a packet, and the maximum data length is 2048
bytes per packet.
The following shows the details of the packet elements. Also, refer to Appendix 5.3 for
an example of packet element data.
(1) Header
Use this element when a specific code/character string exists at the beginning of
a packet.
•
When sending: Sends a specified code and character string.
•
When receiving: Verifies a header and receive data.
The following table is the items.
Item Description Remark
Element Name Set a name of the element. -
Code Type
Select a data type of the setting value.
ASCII String/ASCII Control Code/HEX
-
Set data within 1 to 50 bytes.
Code type Setting range
ASCII String 20
H
to 7F
H
ASCII Control Code 00
H
to 1F
H
, and 7F
H
of control code
HEX 00
H
to FF
H
of hexadecimal data
Setting Value
(Setting example)
ASCII String
: "ABC"
ASCII Control Code: STX
HEX
: FFFF
POINT
y Only one Header can be placed in a packet.
y A Header can be placed only at the beginning of a packet.