Overview: Diagnostics - Siemens Simatic S7-300 CPU 31xC Series Installation And Operating Instructions Manual

Debugging functions, diagnostics and troubleshooting

10.3 Overview: Diagnostics

The differences between forcing and modifying variables
Table 10-1
Characteristics/function
Memory bit (M)
Timers and counters (T, C)
Data blocks (DB)
Inputs and outputs (I, O)
Peripheral inputs (PI)
Peripheral outputs (PO)
User program can overwrite modify/force values
Maximum number of force values
Reference
Details on test functions of the software are found in the
STEP 7 Programming Manual
10.3 Overview: Diagnostics
System errors can occur especially in the commissioning phase. Tracking these errors might
be a time-consuming effort, since they can occur both on the hardware and software side.
Here, the multitude of testing functions ensures commissioning without problems.
Note
Errors during operation are almost always a result of faults or damage to the hardware.
Type of error
Errors the S7 CPUs can recognize and to which you can react with the help of organization
blocks (OBs) can be split into the following categories:
• Synchronous error: Errors you can relate to a specific point in the user program (error
• Asynchronous error: Errors you can not relate to a specific point in the user program
10-4
The differences between forcing and modifying variables
when accessing a peripheral module, for example).
(cycle time exceeded, module error, for example).
Forcing
-
-
-
Yes
-
-
Yes
10
.
Operating Instructions, Edition 08/2004, A5E00105492-05
Modifying Variables
Yes
Yes
Yes
Yes
-
Yes
Yes
-
STEP 7 Online Help
and in the
S7-300, CPU 31xC and CPU 31x: Installation