During PV plant operation, inverter communication disconnection is a common problem. The following describes how to troubleshoot inverter communication disconnection in RS485 communication scenarios.
Troubleshooting Procedure
1. If multiple inverters on an RS485 cable are disconnected, check the first inverter on the RS485 cable. If the upper-level inverter cable is disconnected, the communication of all inverters on the lower-level circuit is affected. Generally, this problem is caused by RS485 cable disconnection. In this case, rectify the RS485 cable fault.
2. If the communication between an inverter on the RS485 cable is interrupted, measure the voltage difference between the upper-level and lower-level RS485 cables. If the voltage difference is abnormal, the RS485 cable is faulty (generally, the voltage difference is about 0.5 V), as shown in the following figure.
3. If the voltage difference between the upper-level RS485 line and the lower-level RS485 line is normal, check whether the inverter open-circuit voltage difference is normal.
4. If the inverter open-circuit voltage difference is abnormal, contact the vendor's engineers to capture the local RS485 packets of the inverter. If the command output is normal, the inverter is normal. If the command output is not normal, the monitoring board may be faulty. Note: In RS485 communication, the shield layer of the RS485 cable is important. If the shield layer is not grounded, the RS485 communication anti-interference capability is weak. As a result, the SUN2000 communication may be abnormal due to interference. See the following figure.
(The shield layer of the RS485 cable is grounded.)
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