Mitsubishi Melsec-L Series User Manual page 155

(2) Reception by received data count (For fixed length reception)
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(a) This method is used to receive messages of the same length (size) from the
external device every time.
(b) When the C24 receives data of the received data count preset in GX Works2
by the user, it sends a reception data read request to the sequence program.
Upon a read request by the C24, sequence program data can be read for
the amount of the data received from the external device.
(c) The received data count default value is set to 511 (words). However, it can
be changed within the size of the receive data storage area depending on
the data contents exchanged with the external device.
POINT
(1) When the receive complete code and received data count are set to GX
Works2, both become valid.
In this case, if the C24 receives the receive complete code before receiving
data that are equivalent to the receive data count, Reception data read request
(X3/XA) is set to ON.
(2) The receive complete code and received data count can be changed in the
following items of GX Works2.
[Various_Control_Specification] screen
complete code designation" or "Received data count designation"
For details, refer to Section 7.2.
10 DATA COMMUNICATION USING THE NONPROCEDURAL PROTOCOL
"For data reception" "Receive
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