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MELSEC-Q
10 TROUBLESHOOTING
(b) Initializing communication error information by writing
Communication error information can be initialized by writing "1" to the
corresponding bit in the buffer memory addresses 0
H
to 1
H
.
The displayed LEDs and communication error information may be turned
on/off in the following cases:
• NEU. to NAK turn on/off depending on the status.
• C/N to SIO turn on when errors occur and keep the ON-status even
after the operation returns to normal.
1) LED and communications error information initialization request area
(address: 0
H
to 1
H
)
The contents of the error information corresponding to each bit in this
request area are the same as those for the LED ON/communication
error status storage area (address: 201
H
to 202
H
).
For more details, see Section 10.1.1 (1).
The following describes the correspondence between the LED OFF
request areas and the LED ON status storage areas:
• Communication error clear request area for CH1 and to turn LED off
(address: 0
H
) LED ON status and communication error status area
on CH1 side (address: 201
H
)
• Communication error clear request area for CH2 and to turn LED off
(address: 1
H
) LED ON status and communication error status area
on CH2 side (address: 202
H
)
2) Example of a program for turning off displayed LEDs
The following shows an example of a program that issues an
initialization request for all the communication error information of CH1
and CH2.
(Input/output signals X/Y00 to X/Y1F of QC24)
Example of TO instruction
Writes 00FF
H
to
address 0
H
and C0FF
H
to address 1
H
.
Turn off command
POINT
(1) Initialization requests are valid only when write operation is performed.
The initialization requests clear all data in the LED ON and communication
error information storage area (201
H
to 202
H
) at the same time.
Furthermore, when initialization of error information on the CH1 and CH2 sides
is requested, XE and XF also turn off.
(2) Data written to the buffer memory address 0
H
to 1
H
is cleared after initialization
processing.
(3) If errors persist even after completion of the initialization processing, the
corresponding communication error information is stored again and the
corresponding bit in the LED ON and communications error status storage
area (201
H
to 202
H
) turns on (1).