Mitsubishi Electric MELSEC iQ-RJ71C24-R2 - Page 342

340
16 TRANSPARENT CODES AND ADDITIONAL CODES
16.5 Handling Transparent and Additional Codes for Bidirectional Protocol Data Communication
Precautions
The additional code data to be added/deleted is not included in the data length, nor will it be subject for sum check code.
Example of request data transmission when ASCII-BIN conversion is disabled
Processing order for transmitting/receiving data
■At the time of reception
• C24 deletes (removes) the additional code designation data from an arbitrary data portion when a transparent code for
receiving is specified.
• C24 stores the arbitrary data portion in the receive area on the buffer memory.
When ASCII-BIN conversion is designated, C24 converts it to binary code data and stores in the buffer memory.
• When the data portion for the designated data length is received, reading the received data is requested of the CPU
module.
If the sum check code is set to 'Yes' in the transmission setting via an Engineering tool parameter settings, reading the
received data is requested of the CPU module upon reception of the sum check code.
■At the time of transmission
• C24 adds the transmission control code to the data to be sent (arbitrary data portion of a transmission message), which is
designated by the CPU module, and transmits it.
When ASCII-BIN conversion is designated, C24 converts it to ASCII code data at first and transmits it.
• When the sum check code is set to be enabled, C24 calculates the sum check code from the transmission message and
add it to the transmission message.
• C24 adds the additional code data immediately before the transparent code/additional code data in respect to arbitrary data
portion, and transmits it when a transparent code for sending is specified.
The figure above shows how C24 processes the data to be transmitted/received when the ASCII-BIN conversion function,
and/or the data communication function by transparent code designation are enabled and disabled.
Use this information as a reference to select the method to send/receive data for data communication with a target device.
05H 02H 02H 3AH00H 12H BCH 0CH
L
01H
HH
(0002H)
10H10H
L
(H) (L)
E
N
Q
D
L
E
D
L
E
00H , 02H
02H , 12H
BCH , 3AH
Additional code
Transparent code
Buffer memory
Message
Sum
check
code
Data length Data section
Additional code : 10H
Transparent code : 02H
Transmission data count/
Receive data count
Transmission data/
receive data
Target device C24
(Transparent code designation) (Sum check code setting) (ASCII-BIN conversion designation)
No No No
Data
reception
(Arbitrary data section only)
Buffer memory
Calculation and check of
sum check code
Deleting
additional code
Deleting transmission
control code (ENQ)
ASCII-BIN conversion of
data length, data section
Reception
area
Yes Yes Yes
Response
transmission
Reception
result storage
area
Adding
additional code
Adding transmission
control code (ACK/NAK)
ASCII-BIN conversion
of error code
Yes Yes
(Error code section only)
No No
Target device C24
(Transparent code designation) (Sum check code setting) (ASCII-BIN conversion designation)
No No No
Data
transmission
Buffer memory
(Arbitrary data section only)
ASCII-BIN conversion of
transmission data count
and transmission data
Calculation and check of
sum check code
Adding
additional code
Adding transmission
control code (ENQ)
Transmission
area
Yes Yes Yes
Response
reception
Deleting
additional code
Deleting transmission
control code (ACK/NAK)
ASCII-BIN conversion
of error code
Transmission
result storage
area
Yes Yes
(Error code section only)
No No