Mitsubishi Melsec-L Series User Manual page 48

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4) ER(DTR) signal (4)
• When communicating data using the nonprocedural protocol, the C24 turns
this signal on or off (on when data is receivable) depending on the amount
of unused memory in the OS area allocated for receive data storage, if
DTR/DSR control is being performed.
Read the receive data from the sequence program, as the receive data is
stored in the OS area when the ER(DTR) signal is OFF.
If DTR/DSR control is not performed, the ER(DTR) signal is always ON.
• If an MC protocol or bidirectional protocol is performing data communication,
this signal turns ON when communications is enabled.
5) DR(DSR) signal (6)
• During DTR/DSR control, if this signal is OFF, the C24 does not send data
to the external device.
Be sure that this signal is always ON when the external device is ready to
receive.
• If DTR/DSR control is not performed, the DR(DSR) signal status is ignored.
6) RS(RTS) signal (7)
• The C24 turns ON/OFF this signal as shown below.
• While the communication system is full-duplex communication, the C24 turns
ON the RS(RTS) signal when the C24 ready (X1E) is ON.
• When the communication system is half-duplex communication, the C24
turns on the RS(RTS) signal when it sends the data to an external device.
• The RS(RTS) signal does not turn OFF even when the receive data cannot
be stored in the C24.
7) CS(CTS) signal (8)
• The C24 does not send data to an external device when this signal is OFF.
• Be sure that this signal is always ON when the external device is ready to
receive.
8) CI(RI) signal (9)
• The CI(RI) signal is used when the modem status is monitored on the C24
side. Connect the modem as necessary.
The CI(RI) signal is not necessary when the modem is not connected.
6 SETTING AND WIRING
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