App - 41 App - 41
MELSEC-Q
APPENDIX
Appendix 7.4.2 Data flow when a receive buffer full error occurs
The following diagram illustrates the flow of data when 1 to 1024 is specified (receive
buffer available) in the receive buffer specification when the communication channel is
opened and a receive buffer full error occurs due to the data received from an external
device.
The 0D
H
(
C
R
) data is specified as the single break character and a maximum of 10
bytes is requested to be received.
Data received after a receive buffer full error is ignored.
Reception data stored in the reception buffer for the amount of characters requested to
be received from the BASIC program, is returned to the BASIC program.
When the processing of the reception request from the BASIC program has been
completed, the following processing is performed.
1) All of the remaining data in the receive buffer is deleted.
2) After processing 1) is completed, data received afterward is again stored in the
receive buffer.(This reception data can be accessed by the BASIC program.)
(BASIC program)
Communication channel open
Result of channel opening
Receive request
Receive buffer
Communication module
Data
"1"
"2"
"3"
"4"
"5"
"6"
"7"
"8"
(OS)
"1"
"2"
Ig
nore
d
"9"
"0"
"@"
"@"
"@"
"@"
Input element
Reception
result
(Error occurrence)
"1"
"2"
"3"
"4"
"5"
"6"
"7"
"8"
"9"
"0"
"3"
"9"
"0"
"@"
"@"
"@"
"@"
"@"
"A"
"B"
"@"
"@"
"@"
"@"
"@"
ZOPEN to
ZRECEIVE to
"@"
"@"
"A"
"B"
"Y"
"C"
"Y"
"Z"
"@"
"@"
"@"
"@"
"@"
"1"
Ig
nore
d
"@"
"CR"
"CR"
