UrvtApv9vhtvphqAhy@yvvhvS7-300 Automation System, Hardware and Installation: CPU 31xC and CPU 31x11-4 A5E00105492-03" Pr
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Errors the S7 CPUs can recognize and to which you can react with the help oforganization blocks (OBs) can be split into the following two categories:• Synchronous errors: Errors you can relate to a specific point in the userprogram (e.g. error when accessing a peripheral module).• Asynchronous errors: Errors you can relate to a specific point in the userprogram (e.g. cycle time exceeded, module error).@
ChqyvtProgramming with foresight and, above all, knowledge and proper handling ofdiagnostic tools puts you into an advantageous position in error situations:• You can reduce the effects of errors.• It makes it easier for you to locate errors (e.g. by programming error OBs).• You can limit downtimes.9vhtvpvuG@9qvyhSIMATIC S7 hardware offers diagnostics with LEDs.These LEDs are implemented in three colors:• Green LEDs report regular operation (e.g. supply voltage is applied).• Yellow LEDs indicate special operating states (e.g. "Force" is active).• Red LEDs report errors (e.g. bus error)A flashing LED also indicates a special event (e.g. memory reset).8
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rprNotes on diagnostics with LEDs are found in the Chapter below.Notes on diagnostics of I/O modules capable of diagnostics are found in therelevant Manual.
