App - 35 App - 35
MELSEC-Q
APPENDIX
(3) When the RS (RTS) and CS (CTS) control signal lines as well as
the ER (DTR) and DR (DSR) control signal lines are looped back
on the communication module side
Communication
module
(Signal name)
RD(RXD)
SD(TXD)
ER(DTR)
SG
DR(DSR)
RS(RTS)
CS(CTS)
Connector
RS-232C
External
device
Connector
If either the RS (RTS) or the ER (DTR) control is disabled, data can be received
from the external device but data cannot be sent to the external device. In this
case, turn the RS (RTS) control signal ON using processing code 32 of the
ZCNTL instruction and disable the DR (DSR) control to send data to the external
device.