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Questions about the use of s7 PLC
When using S7Interface, some S7Interface can connect to many points, and some S7Interface will be disconnected if the number of connections is too large, please see the picture, as if: Negotiated Pdu Lenght is related to this value. May I ask how Negotiated Pdu Lenght is set? Why is it 480 or 240? If Negotiated Pdu Lenght is 240, too many signals cannot be connected.
There is also a question about: how to use the Area Read Write Mode, if I need to read 56 points from the PLC's DB block and write 12 points, how should I fill in the configuration.
Looking forward to your reply very much！
Answer
Hi, I can't tell you in detail why the negotiated Pdu lenght is like that. We use Sharp7 as a basis library for the S7 communication. I think this defines the length of the telegrams but it does not defines the number of the signals. If needed multiple telegrams are send for covering all signals. On AreaReadWrite Mode you sould enter min and max adress - so if your DB is 100.X to 140.X you should enter 100 and 140.
Customer support service by UserEcho
Hi, I can't tell you in detail why the negotiated Pdu lenght is like that. We use Sharp7 as a basis library for the S7 communication. I think this defines the length of the telegrams but it does not defines the number of the signals. If needed multiple telegrams are send for covering all signals. On AreaReadWrite Mode you sould enter min and max adress - so if your DB is 100.X to 140.X you should enter 100 and 140.