MITSUBISHI ELECTRIC QJ71C24N - Manual (Page 125)

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MELSEC-Q
6 DATA COMMUNICATION USING THE NON PROCEDURE PROTOCOL
(2) Reception by received data count (For fixed length reception)
(a) This method is used to receive messages of the same length (size) from the
external device every time.
(b) When the Q series C24 receives data of the received data count preset in
GX Configurator-SC by the user, it sends a reception data read request to
the sequence program.
When the sequence program receives the read request from the Q series
C24, it reads data up to the received data count 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
Configurator-SC, both become valid.
In this case, if the Q series C24 receives the receive complete code before
data corresponding to the received data count, it outputs (X3/XA: ON) a
reception read request signal to the sequence program.
(2) For details on how to change the receive complete code and received data
count, see Section 8.4.7.