The following example demonstrates how to check the cause of CPU shutdown through the diagnostic buffer. Write a data transfer program in the main program OB1 to send 23 to DBW0 in data block DB1, save the project, and download OB1.
In the project tree of the project view, double-click "Online and Diagnostics" under PLC1 station to open the Online Diagnostics dialog box. Click the "Go to Online" button in the toolbar to enter online connection mode. Click the Operator panel in the online tools, and then click the "Run" button. Since we haven't created data block DB1, we can see that the CPU cannot run and is in a stopped state.
Click on the Diagnostic Buffers to view its contents, where you can see recent events. Event 1 indicates startup information, and Event 2 indicates that DB1 is not loaded. This allows you to find the cause of the CPU malfunction.
The diagnostic buffer records multiple events simultaneously. These events need to be combined to analyze and determine the cause of the CPU shutdown. Selecting a specific event and clicking the "Open Block" button will directly open the block where the error occurred.
The above describes how to use the diagnostic buffer of Siemens PLC1200 and how to check the cause of CPU shutdown. Please feel free to contact us for further information.
