I believe that everyone often encounters the situation that the DP slave station is dropped in daily work, which causes the system to run indefinitely. Xiaobian has dealt with the problem of the DP slave station dropping of several systems in the past few days, which makes the head big. Let's share with you the troubleshooting process of a classic DP slave drop.

1. System topology

The system adopts the CPU of Siemens S7-400, and the slave station is the PROFIBUS-DP communication connection composed of ET200M, speed encoder and linear position sensor. The topology diagram is shown in the following figure:

In the topology shown in the figure above, considering that the ingress and egress devices are far away from the CPU, and at the same time considering the problem of interference, the optical fiber to DP communication method is used.

2. Description of the fault phenomenon

The on-site personnel reported that the circulating pump and the main pump of the hydraulic station suddenly stopped at the same time during the normal operation of the unit. The initial consideration is that the hydraulic station stops due to the unsatisfactory operating conditions of the circulating pump. The parameters of the operating conditions of the hydraulic station are monitored through IBA, and it is found that all parameters of the inlet ET station are lost at the same time. All dropped.

That is, the part of the ET station shown in the figure below is dropped.

Based on the above situation, consider the PROFIBUS_DP network drop caused by the interference of the entrance equipment. Through investigation, the processing of possible interference sources is difficult to find specific points due to the complicated path and the non-standard cable laying during construction, and the effect after processing is not obvious.

　　标签：DP编码器