4/22/2020 6:48 PM | |
Joined: 9/27/2006 Last visit: 7/14/2024 Posts: 12268 Rating:
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Hello Rodeey; You will find information of th OBs used for your CPU 319 in the System and Standard Functions manual for S7-300 and S7-400 CPUs, chapter 1. https://support.industry.siemens.com/cs/ww/en/view/109751826 OBs are blocks of code that must be created and downloaded to your CPU program, but are not called by the user program. They are an interface between the CPU's operating system and the CPU hardware and software. Think of all that happens when you touch your mouse of a keyboard key on your computer. A lot of code is processed by the operating system without you calling it directly, it happens without your knowledge or complete attention. Same thing with an OB on your CPU. Some of the OBs that can be used by your CPU are called by the operating system in response to the detection of a fault in the system. The screenshot below shows a list of so-called diagnostic OBs that will be used to collect information on the cause and origin of a fault when the specific type of fault is detected. For example, OB 86 is dedicated to remote I/O station faults. If a remote rack reposts a fault and OB 86 is not found on the CPU program, the CPU will go to STOP mode, and the BF LED on the CPU will light uo. If OB 86 is found (even without a line of code inside it), the local data of OB 86 (look at that section in the manual suggested) is sufficient to provide data (time stamp, affected node address, affected module addresses...) on the fault to the diagnostic buffer, where it can be retieved by the user. Also, the interrupt of the OB 86 call is sufficient to bypass the fault, so the CPU willl remain in RUN Mode, with the diagnostic LEDs active (SF and BF) so the user does realize there is a problem in the system. This is a very quick introiduction, look at the contents of the manual for more details.There are more threads on the subkct here (use the search box on the right of this page to look for them) and on the web: https://control.com/forums/threads/s7-300-diagnostics-obs.21115/ Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 04/23/2020 11:53:13 |
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