Mitsubishi Electric MELSEC iQ-R Series User Manual page 285

Remarks
The following shows the difference between the reception methods (Method 0 and Method 1) in regard to how to treat the
received data when data in combination of (a start frame + and arbitrary data portion) is received.
■When data is received using Method 0 (combination (1-C))
• C24 regards all arbitrary data portions as valid data after a start frame has been received, and stores it sequentially in the
receive area.
• C24 issues a read request to the CPU module each time arbitrary data portions, which are equivalent to the receive end
data quantity, are received, and repeats this process.
Receive data
First frame
Ignored
■When data is received using Method 1 (combination (1-D, 1-E))
• C24 regards arbitrary data portions, which are equivalent to the 'method 1 dedicated receive end data quantity' specified for
combination of the received start frames, as valid data after a start frame has been received, and stores it in the receive
area. It then issues a read request to the CPU module.
• Any received data after data, which is equivalent to the 'method 1 dedicated receive end data quantity', has been received
up to the next start frame will be ignored. (Data will not be stored in the receive area.)
Receive data First frame
Ignored
Arbitrary data
For the received For the received
data count data count
Stored in the
reception area
reception area
Arbitrary data Receive data
For received data count
for format 1 only
Stored in the Ignored
reception area
: Reception start timing
: Receive complete timing (read timing)
Stored in the
First frame Arbitrary data
For received data count
for format 1 only
: Reception start timing
: Receive complete timing (read timing)
15 DATA COMMUNICATIONS USING USER FRAMES
Stored in the
reception area
15.2 Data Reception
15
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