How to read the data value of the connected slave
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I would like to ask you a simple question about reading the slave station value. We have a displacement sensor that communicates with Siemens PLC S7-300 as a DP slave. The displacement sensor will continuously transmit the currently measured distance value to the PLC in real time. I am in the PLC, how can I receive and view the passed values? Can you tell me specifically what block to use, what address to check, etc.? I don’t know much about PLC, so I’m sorry to bother you! Thank you in advance
Step7: Go to the online status and there is an online status bar on the right side to view changes in online parameters.
In fact, what you are saying now is not very clear. 1. You need to find out whether your displacement sensor uses DP protocol with the PLC for data transmission. 2. If this is the case, if your displacement sensor has its own driver or Siemens supports your displacement sensor, you can directly hang on the 300 DP bus for communication. 3. If your sensor does not have such a powerful function (I think not. ) Then the 300 PLC needs a special DP communication card to perform master-slave communication and data exchange. There is no way to explain this clearly in one or two sentences. Anyway, that’s the plan. Displacement sensors that are not ordinary enough can directly perform 4-20Ma transmission, why do you need DP communication? I don’t understand.
Take a certain model of SIMENS frequency converter that supports DP as an example. After it is used as a slave station, its parameters are mapped to the AI/AO template, and it also occupies the PIW and PQW addresses. You can directly see it. If the device you mentioned does support the DP protocol, it should be like this.