Mitsubishi Electric MELSEC iQ-R Series User Manual page 247

■When C24 is designated to "Non-priority"
Target device
CPU module
SD(TXD) (Send Data)
RS(RTS) (Send Request)
CS(CTS) (Send Possible)
CD(DCD)
(Data Carrier Detect)
RX(RXD) (Receive Data)
The contents of steps  and  below are different from those of the case "Priority" is designated.
 When transmitting data, check the RS (RTS) signal. If the RS (RTS) signal is OFF, turn ON the CD (DCD) signal. If the RS
(RTS) signal is ON, wait until it is turned OFF, then turn ON the CD (DCD) signal.
 Transmit data after turning ON the CD (DCD) signal.
 After data transmission is completed, turn OFF the CD (DCD) signal.
 Keep transmitting data to C24 even if the RS (RTS) signal is turned ON during data transmission. (Simultaneous
transmission occurred.)
 After transmission from the target device is completed, transmit data from C24 to the target device. (Page 246 Timing
when transmitting data from C24)
*1 For the transmission content, refer to the following section.
Page 246 Timing when transmitting data from C24
■Remarks
When using the DTR/DSR transmission control function, transmit data from the target device to C24 as shown below in both
cases above. (Page 236 DATA COMMUNICATIONS USING DC CODE TRANSMISSION CONTROL)
• When C24 ER (DTR) signal is turned OFF, terminate data transmission.
• When C24 ER (DTR) signal is turned ON after data transmission is terminated, restart data transmission (transmit from the
terminated part of the data).
Data A
Data C-1
Ò
Ó
Ô
Data A
12 DATA COMMUNICATIONS USING HALF-DUPLEX COMMUNICATIONS
Continue data
transmission.
Data B
Data C-1 Data C-2
Retransmission
Since the C24 does not have priority,
when the CD(DCD) signal is turned
ON, it terminated transmission.
Data C-2
Õ
Ö
The C24 stores
the received data.
Data B
12.2 Data Transmission and Reception Timing
(*1)
245
12