Mitsubishi MELSEC LJ71C24, Руководство пользователя

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11 DATA COMMUNICATION USING THE BIDIRECTIONAL PROTOCOL
(b) Data length
This indicates the number of bytes or words for the data portion of the
message.
The unit of data length (words/bytes) is in accordance with the word/byte
units designation in GX Works2.
1) For data communication from the external device to the C24
The C24 checks the length of the data received.
When the reception is normal, the C24 stores the receive data in the
receive data storage area of the C24 buffer memory, assigning the first
byte as the lower byte (L).
2) For data communication from the C24 to the external device
The length of the transmission data is the number of the transmission
data designated by the sequence program using the BIDOUT instruction.
The C24 sends this value as is from the lower byte (L).
(c) Data portion
This consists of an array of original one-byte data to be transmitted to the
external device side, which can handle 00
H
to FF
H
code data.
1) For data communication from the external device to the C24
If the receive data portion is normal, the C24 takes the codes as is and
stores them in the receive data storage area in sequence, beginning with
the youngest address.
The storage size is in accordance with the data length in the message
(Refer to item (b) above) and the word/byte units designation in GX
Works2.
2) For data communication from the C24 to the external device
The transmission data portion is the number of the transmission data
designated by the sequence program using the BIDOUT instruction.
The C24 sends the transmission data using the existing codes until the
transmission data count is reached in accordance with the word/byte
units designation in GX Works2 to the transmission data designation
area.