Siemens Simatic S7-300, Hardware And Installation Manual, Page: 166 / 242

Testing functions, Diagnostics and Fault Elimination
S7-300 Programmable Controller Hardware and Installation
10-6
A5E00105492-01
help of the diagnostic buffer and of the stack content. You can also check whether
a user program will run on a specific CPU.
Hardware diagnostics give you an overview of the PLC status. In an overview
symbols can display the error status of every module. A double-click on the faulty
module opens detailed error information. The scope of this information depends on
the specific module. You can view the following information:
•
Display of general information on the module (e.g. order No., version,
designation) and module status (e.g. error).
•
Display of module errors (e.g. channel error) in the central I/O and DP slave.
•
Display of messages from the diagnostic buffer.
For CPUs you can also view the following module status information:
•
Cause of an error in the user program cycle.
•
Display of the cycle time (longest, shortest and last cycle).
•
Options and utilization of MPI communication.
•
Display of performance data (number of possible /IOs, memory bits, counters,
timers and blocks).
Details on diagnostic options in STEP 7 and practical related procedures are found
in the Manual Programming with STEP 7 and in the HW Config Online Help.
10.5 Diagnostics with LEDs
Introduction
Diagnostics with LEDs is an initial tool for error localization. Usually you evaluate
the diagnostic buffer for further error localization.
The buffer contains plain text information on the error that has occurred. Here you
can find, for example, the number of the matching error OB. You can prevent the
CPU from switching to STOP mode by generating this OB.