Mitsubishi Electric MELSEC iQ-RJ71C24-R2 - Page 282

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15 DATA COMMUNICATIONS USING USER FRAMES
15.2 Data Reception
■Reception of combination (1-B)
This is a method that message to be received by the CPU module side are all transmitted in a fixed format from a target
device.
C24 starts the reception processing when data of the same arrangement as the start frame is received.
When data of the same arrangement as the final frame is received, a read request is issued to the CPU module.
Since there is 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 start frame will be ignored.
• The receive end data quantity initially set to C24 uses the default value.
Ex.
When ACK is registered as the start frame, and CR+LF is registered as the final frame
■Reception of combination (1-C)
This is a method that the start of data transmission from a target device to the CPU module side is notified by a start frame, an
arbitrary data portion of a fixed length is repeatedly transmitted from a target decide after that.
After the start frame is received, the subsequent received data will be handled as arbitrary data portion.
C24 starts the reception processing when data of the same arrangement as the start frame is received.
A read request is repeatedly issued to the CPU module when an arbitrary data portion, which is equivalent to the receive end
data quantity initially set to C24, is received.
Precautions
• Any received data prior to the start frame will be ignored.
• The receive end data quantity initially set to C24 should be a data quantity for an arbitrary data (fixed length) transmitted
from the target device.
• Reception processing by the receive end code initially set to C24 will not be performed. Received data of a receive end
code are treated as an arbitrary data portion.
Ex.
06H 0AH0DH
A
C
K
C
R
L
F
First frame : ACK
Last frame : CR, LF
Receive data
: Reception start timing
: Receive complete timing (read timing)
Ignored Stored in the reception area
The received data count is "0".
Receive data
Arbitrary data
First frame
For the received
data count
For the received
data count
: Reception start timing
: Receive complete timing (read timing)
Ignored Stored in the
reception area
Stored in the
reception area