10 TROUBLESHOOTING
10.3.13Troubleshooting when it is unclear whether the communication error cause is in the Q series C24 or an external device
Symptom | Cause |
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| Corrective action | MC |
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| • Test the Q series C24 as described below to |
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| check where the cause is. |
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| 1) Check the hardware. |
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| • The Q series C24 must be installed firmly. |
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| • The pins of the Q series C24 must not be |
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| bent or otherwise abnormal. |
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| 2) Test the Q series C24 alone. (See Section |
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| 4.7.) |
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| • ROM/RAM/switch test must not generate |
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| any errors. |
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| • Self loopback test must not generate any |
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| errors. |
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| 3) Check the state of the PLC CPU. |
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| • There must not be any errors that stop |
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• Whether the |
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| PLC CPU operation. |
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| Note |
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communications error |
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| • | The following methods are available for |
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cause is in the Q series | |
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| testing if normal communications are possible |
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C24 or an external |
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| with the Q series C24 alone. |
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device is unclear. |
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| 1) With one the Q series C24, set CH1 and |
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| CH2 to the non procedure protocol and |
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| connect the wiring the same as for the self |
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| loopback test and transmit data from one |
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| channel and receive the transmitted data |
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| at the other channel. If the transmitted |
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| data and the received data are the same, |
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| transmit and receive processing is |
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| performed normally. |
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| 2) When two Q series C24 are available, set |
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| one Q series C24 to the non procedure |
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| protocol and the other Q series C24 to a |
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| dedicated protocol and transmit an MC |
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| protocol message from the non procedure |
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| protocol station. If the MC protocol station |
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| returns the transmit message normally, |
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| transmit and receive processing is |
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| normal. |
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Bidirectional Non procedure
10 - 40 | 10 - 40 |