Mitsubishi MELSEC QJ71C24, User Manual

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MELSEC-Q
11 TROUBLESHOOTING
11.1.3 Reading the RS-232 control signal status
This section explains how to read the control signal status stored in the buffer memory
during communication using RS-232 interface.
When GX Configurator-SC is used, check the status using the "Transmission control
and others monitor/test" screen (see Section 9.6.3).
When a transmission problem occurs, read operation is executed to check the signal
on/off status of the RS-232 interface.
(1) RS-232 control signal status (address: 254
H
/264
H
)
The status of the RS-232 signals is stored as follows:
REMARKS
(1) For more details on signals for RS-232, see Section 3.2.1.
(2) Signals output from the Q series C24 side (RS(RTS) and ER(DTR)) are
controlled by the operating system (OS) of the Q series C24.
They cannot be directly controlled by the sequence program.
(3) There is a maximum delay of 100 ms in signal status stored in the buffer
memory above.
(2) Example of a program that reads from RS-232 control signal status
(address: 254
H
/264
H
)
The following shows an example of a program that reads the RS-232 control
signal status.
(input/output signals X/Y00 to X/Y1F of the Q series C24)
Example of FROM instruction