It must be ensured that the receiving CPU does not confirm the reception of global data. Two-way connection: the connection between two CPUs: each CPU can send and receive a GD packet. Unidirectional connection: A CPU can send GD packets to multiple CPUs. The GD ring is identified by the GD ring number. Exchange data in the form of data packets. Data exchange refers to the connection between CPUs connected to a unidirectional or bidirectional GD ring.
Global data (GD) can be: data timers and counter functions in theĭata blocks. Global data communication is used to exchange small-capacity data.
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If such a site selection is necessary, the size of the process image must be adjusted accordingly (in the Properties of the CPU).ĥ: How to perform basic communication of global data in S7 CPU? What should I pay attention to when communicating?
Therefore, these configuration rules do not support this situation: for example, an input double word is configured on address 254 of a 256-byte input process image. Please note that the created data area (such as a double word) cannot be configured on the boundary of the process image, because in this data block, only the area below the boundary can be read into the process image, so it is impossible to access from the process image data. If OB81 is not available, the CPU will remain running when the power supply fails.Ĥ: What issues should be paid attention to when assigning addresses to the I / O modules (centralized or distributed) on the S7CPU? If OB81 is not configured, the CPU will not enter the STOP operating state. In the event of a battery failure, if the BATT.INDIC switch in battery detection is activated, the S7-400 only accesses OB81. After the error is corrected, visit OB81 again. If an error in the power supply (S7-400 only) or the buffer triggers an event, the CPU operating system accesses OB81. Two different times are given on the Startup tab in the CPU Properties dialog.ģ: How to determine the power supply or buffer error, such as: battery failure? When using a DP slave on the PROFIBUS interface of the CPU to operate a PROFIBUS network, you want to check whether the desired configuration matches the actual configuration during startup. In the new module, the F monitoring time is set to 150 milliseconds.Ģ: When the DP slave is not available, what is the monitoring time of the S7-300 CPU on PROFIBUS? To ensure that the scan interval of OB35 is different from the F monitoring time, make sure that the F monitoring time is greater than the OB35 scan interval. However, since OB 35 is called only every 100 milliseconds, a communication failure will occur. You have set the F monitoring time of the F I / O module to 100 milliseconds, so you must address the I / O module at least once every 100 milliseconds. Moreover, you have accepted the default settings for all monitoring times and are willing to receive "communication failure" messages. Using CPU S7 315F, ET 200S and fail-safe DI / DO modules, then you will call the fail-safe program of OB35. 1: How to avoid the "communication failure" message when using CPU 315F and ET 200S?
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