Mitsubishi Electric MELSEC iQ-RJ71C24-R2 - Page 283

15 DATA COMMUNICATIONS USING USER FRAMES
15.2 Data Reception
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15
Reception with the start frame (combination 1-D, 1-E) (reception using Method 1)
This is a method that an arbitrary data portion, which is equivalent to the 'Method 1 dedicated receive end data quantity'
initially set to C24, is transmitted from a target device with a start frame.
C24 starts the reception processing when data of the same arrangement as the start frame is received.
When an arbitrary data, which is equivalent to the specified 'Method 1 dedicated receive end data quantity', is received, the
arbitrary data portion is stored in the receive area on the buffer memory and a read request is issued to the CPU module.
• Method 1 dedicated receive end data quantity
The receive end data quantity for data reception by using Method 1 is referred to as 'method 1 dedicated
receive end data quantity'.
It can be specified with the number of word/byte of "0" or bigger (the unit depends on the word/byte units
designation) for each combination of the start frame and the final frame, which specifies Method 1 (up to 4
combinations).
Precautions
• Any received data prior to the start frame will be ignored.
• The receive end data quantity initially set to C24 is not used.
• 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.
• For reception using Method 1, set "No designation" to the final frame.
Ex.
By specifying a user frame, in which only ACK (06H) is registered, as the start frame and also the 'method 1 dedicated receive
end data quantity' for an arbitrary data portion as 0 bytes, a read request will be issued to the CPU module upon the reception
of a 1-byte ACK.
Ex.
By specifying a user frame, in which only NAK (15H) is registered, as the start frame and also the 'method 1 dedicated receive
end data quantity' for an arbitrary data portion as 2 bytes, a read request will be issued to the CPU module upon the reception
of NAK + 2-byte data.
15 H 34 H 12 H
(1234H)
N
A
K
First frame: NAK
Receive data
For received data count
for format 1 only
: Reception start timing
: Receive complete timing (read timing)
Ignored Stored in the
reception area