10 TROUBLESHOOTING

MELSEC-Q

(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 0H to 1H.

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: 0H to 1H)

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: 201H to 202H).

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: 0H) LED ON status and communication error status area on CH1 side (address: 201H)

•Communication error clear request area for CH2 and to turn LED off (address: 1H) LED ON status and communication error status area on CH2 side (address: 202H)

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

Turn off command

Writes 00FFH to address 0H and C0FFH to address 1H.

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 (201H to 202H) 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 0H to 1H 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 (201H to 202H) turns on (1).

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