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10.
COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
(3)
Data area
The data of O O H to FFH code can be processed in a string of 1-byte
data as the send data.
(a) Data send from an AJ71C24 to a computer
The data area to be transmitted is the value written to the send data
storage area of the AJ71C24 buffer memory by the TO instruction
in a sequence program.
The AJ71 C24 transmits the data according to the designated length
and bytelword units sequentially from the lower address in un-
changed codes.
(b) Data send from a computer to an AJ71C24
The data area received is written to the received data storage area
sequentially from the lower address in unchanged codes as they
are received.
The data length to be written is determined by the data length in
the received message and the designated wordlbyte units.
(4) Check sum
The check sum is the lower 2 bytes (16 bits) of the result obtained by
adding the data length and the data area in the message as binary data.
If the setting at address 115H is " I " , the check sum is not required.
(a) Data send from an AJ71C24 to a computer
The AJ71C24 calculates and adds the check sum.
If the check sum is not processed, the check sum is not transmitted.
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