4. Troubleshooting (PROFIBUS DP)
♦ Causes of Error
Possible Cause |
| Examination Method | Countermeasure |
{ Disconnected | (1) | Check that terminating | Fix the problem. |
terminating resistors |
| resistors are connected to |
|
{ Cable disconnection |
| both ends of the network. | How to find the trouble |
{ Disconnected | (2) | Measure resistance | point: |
connector |
| between signal wires with | Remove the terminating |
{ Disconnected signal |
| device power supply OFF. | resistor on one end of the |
wire | → Normal: 100 to 120 Ω | network. The trouble point | |
| z Measuring point: Connection | is where resistance changes | |
| of the trouble unit | from 220 Ω. | |
| z For detail, refer to the section |
| |
| 4.2.3.1 Connection Problem. |
| |
{ Loose connector | Check for the connection of | Connect the connectors and | |
{ Loose signal wire | connectors and signal wires. | signal wires again. | |
| → The connectors and signal |
| |
| wires should be firmly |
| |
| connected. |
| |
| z Checkpoint: all stations and |
| |
| all branch taps |
| |
| z For details, refer to the |
| |
| section 4.2.3.2 Loose |
| |
| Connector and Signal Wire. |
| |
{ Noise | Check the noise intrusion via | Take countermeasures | |
(external cause) | the following paths (1) to (3). | against noise. | |
| (1) | Noise via shield |
|
| (2) | Induced noise via |
|
|
| communication cable |
|
| (3) | Device power supply |
|
| → For details, refer to the |
| |
| section 4.2.3.3 Noise |
| |
| Intrusion. |
| |
{ Broken unit | Replace the trouble unit with a | Replace the unit with a new | |
| new one. | one. | |
| → Verify whether the problem |
| |
| is fixed. |
| |
z No cause is | Identify the trouble point by |
| |
identified. | dividing the network. |
| |
| → For details, refer to the |
| |
| section 4.2.3.4 Broken Unit |
| |
| Examination. |
| |
120 | Fieldbus I/O Rev.6 |
