Mitsubishi Electric MELSEC iQ-R Series User Manual page 284

Reception without the start frame (combination 2-A, 2-B) (reception using Method 0)
■Reception of combination (2-A)
This is a method that a user frame is used as the final frame in place of the end code for nonprocedural protocol data
reception and transmitted from a target device with an arbitrary data portion.
C24 starts the reception processing when the arbitrary data portion is received.
When data of the same arrangement as the final frame is received, the arbitrary data is stored in the receive area on the buffer
memory and a read request is issued to the CPU module.
Precautions
• Any received data prior to the final frame will be all treated as an arbitrary data portion.
• The receive end data quantity initially set to C24 should be a data quantity that exceeds the size of the arbitrary data to be
received.
• C24 performs the following processing with respect to the received data that is the same as the receive end code initially
set to C24.
When it is included in the arbitrary data portion: C24 performs the reception processing by the receive end code.
When it is included in the final frame: C24 does not perform the reception processing by the receive end code.
Ex.
By registering ETX + CR + LF as the final frame, a read request is issued to the CPU module when the end of the received
data receives a message of ETX + CR+ LF.
Arbitrary data
Stored in the reception area
■Reception of combination (2-B)
This is a method that a user frame is used as the final frame in place of the end code for nonprocedural protocol data
reception and data in a fixed format is transmitted from a target device.
C24 issues a read request to the CPU module when data of the same arrangement as the final frame is received.
Upon data reception of this combination which contains no arbitrary data portion, the receive data quantity will be "0" when a
read request is issued to the CPU module.
Precautions
• Any received data prior to the final frame will be all treated as an arbitrary data portion.
• The receive end data quantity initially set to C24 uses the default value.
• When received data that is the same as the receive end code initially set to C24 is included in the final frame, C24 does not
perform the reception processing by the receive end code.
Ex.
By registering ACK + CR + LF as the final frame, a read request is issued to the CPU module when the end of the received
data receives a message of ACK + CR + LF.
A
C
K
06H
Stored in the reception area
The received data count is "0".
15 DATA COMMUNICATIONS USING USER FRAMES
282
15.2 Data Reception
E C L
T
X R F
03 0D 0A
H H H
C L
Last frame: ACK, CR, LF
R F
0DH 0AH
: Reception start timing
: Receive complete timing (read timing)
Last frame: ETX, CR, LF
: Reception start timing
: Receive complete timing (read timing)