10TROUBLESHOOTING
(3)Checking by GX
Display the "Monitor/test others" screen.
For details on display screens, see Section 8.6.9 of the User's Manual (Basic).
(4) Description of LED ON status and communications error status
| Status |
| Description when ON | Description when OFF |
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| Related protocol | ||
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| Initial |
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No. | signal | Description | (when LED is turned on | (when LED is turned off | state | MC |
| procedure | Bidirection- |
| name |
| (1)) | (0)) |
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| protocol | al protocol |
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1 | SD WAIT | Transmission wait status | Waiting for data | Data transmission start | OFF |
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transmission |
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| Overrun or framing |
| OFF |
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| error occurred. |
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2 | SIO | SIO error status | OS area is full. | Normal |
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| Received data was |
| OFF | — |
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| deleted. |
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3 | PRO. | Communication protocol | Error occurred. | Normal | OFF |
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| error status |
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4 | P/S | Status of parity error or | Error occurred. | Normal | OFF |
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sum check error |
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5 | C/N | Access status with the | ( 1) | Normal | OFF |
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PLC CPU |
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6 | NAK | Abnormal completion | Abnormal completion | Normal completion | OFF |
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status | transmission | transmission |
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7 | ACK. | Normal completion | Normal completion | Abnormal completion | OFF |
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status | transmission | transmission |
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| Neutral status |
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8 | NEU. | Waiting to receive | Neutral | Command reception | ( 2) |
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| command |
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9 | CH2. ERR | Error occurrence status | Switch setting error |
| OFF |
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on CH2 side | Mode switching error |
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| Error occurrence status | Transmission error | Normal |
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10 | CH1. ERR | Reception error |
| OFF |
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| on CH1 side |
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1 C/N turns on in the following cases:
•An external device issued a data read request to the PLC CPU when write during RUN is set to prohibit in the switch settings by GX Developer (see Section 4.5.2).
For functions that cannot be used when write during RUN is set to prohibit, see the explanation section in each command list of the Reference Manual.
•When an error has occurred during access between the Q series C24 and the
PLC CPU.
2 NEU. is valid when a target interface is set to use the MC protocol.
When the target interface is set to other than the MC protocol, the status of NEU. is off.
10 - 4 | 10 - 4 |