App - 38 App - 38
MELSEC-Q
APPENDIX
Appendix 7.4 Data Flow When an Error Occurs During Data Reception
Appendix 7.4.1 Data flow when a transmission error occurs
The examples in the following figures illustrate the flow of data when a transmission
error (frame error, parity error, overrun error) occurs while receiving data 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.
(1) When there is no receive buffer
If a transmission error occurs while a BASIC program is receiving data from the
host after requesting to receive data, the data received up to the time when the
transmission error occurred is returned.
A transmission
error occurs.
"A"
"B"
"C"
"D"
"F"
(BASIC program)
Communication channel open
Result of channel opening
Receive request
Communication module
Data
(OS)
Ig
n
o
re
d
Input element
"A"
"B"
"C"
"D"
ZOPEN to
ZRECEIVE to
Data
"A"
"B"
"C"
"D"
"E"
"F"
Input element
"A"
"B"
"C"
"D"
"E"
"F"
ZRECEIVE to
"CR"
Data prior
to reception
Ig
n
o
re
d
Data
Da
ta
p
ri
o
r t
o
re
cep
ti
o
n
Reception result
Reception result
Receive request
(Error occurrence)
"CR"
"CR"
Ig
n
o
re
d
