Mitsubishi MELSEC LJ71C24, User Manual

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9 DATA COMMUNICATION USING THE PREDEFINED PROTOCOL
(7) Check Code
Use this element when an element indicating check code data is included in a
packet.
The C24 automatically calculates a specified check code at timing of
sending/receiving, and adds it to a send packet or detects an error of a receive
packet.
The following table lists the items.
Item Description Remark
Element Name Set a name of the element. -
Processing Method
Select a calculating method.
Horizontal parity/Sum check/16-bit CRC (for MODBUS)
-
Code Type
ASCII Hexadecimal
ASCII Decimal
HEX
When sending: Select a format in which a
calculated check code is sent.
When receiving: Select a format in which data
are received.
Not settable when
"Processing Method"
is "16-bit CRC (for
MODBUS)"
Data Length
Select the data length on the line (byte).
The range is 1 to 4.
Not settable when
"Processing Method"
is "16-bit CRC (for
MODBUS)"
Forward direction
(Upper byte Lower byte)
When sending: Sends a calculated check
code, from the upper byte.
When receiving: Manipulates receive data as a
check code, from the upper
byte.
Data Flow
Reverse direction
(Lower byte Upper byte)
When sending: Sends a calculated check
code, from the upper byte.
When receiving: Manipulates receive data as a
check code, from the upper
byte.
Effective only if the data length
is 2 to 4 (bytes).
Not settable when
"Processing Method"
is "16-bit CRC (for
MODBUS)", or when
the "Data Length" is
set to "1 (byte)".