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Troubleshooting
6.2
Responding to Diagnostic Events
If an error is detected by the controller, the error condition is logged in the
diagnostic buffer as a diagnostic event. The diagnostic events that are typically
associated with distributed I/O can cause the controller to execute the following
OBs :
•
OB 40 responds to hardware interrupts (process alarms) generated by an I/O
module with configured interrupt capability.
•
OB 82 responds to diagnostic interrupts generated by an I/O module with
configured diagnostic interrupt capability.
•
OB 83 responds to module removal/insertion at a DP Slave, (for example, ET
200M), which has been configured for module pull/plug support.
•
OB 84 responds to CPU hardware faults or PC failure. With the CPU 41x-2
PCI, causes include:
-
CPU hardware faults
-
PC is switched off, is starting up, or has crashed. For this reason, you must
always program OB 84 so that the CPU 41x-2 PCI can be operated
independently of the PC.
•
OB 85 responds to a priority class error. There are multiple causes for OB 85
relating to the DP I/O system. If the controller attempts to copy a module's
inputs to (or outputs from) the process image during the I/O cycle, and the
module is not operational, then OB 85 is executed.
•
OB 86 responds to a station failure or some other interruption of the physical
network (such as a short circuit).
•
OB 122 responds to an I/O access error by the user program. If OB 122 is not
programmed, the controller goes to STOP mode.
You can use SFC 39 to SFC 42 to disable, delay, or re-enable any of these OBs. If
a non-loaded OB was requested, the controller goes to STOP mode.
The local variables for these OBs contain restart information indicating the cause
for executing the OB. The program for the OB can use this information for
responding to the event. You can also use SFC 13 (DPNRM_DG) to read the
diagnostic information from a DP slave.
For information on using OBs and SFC 13, refer to the STEP 7 online help.
86
Hardware Installation and Operating Manual, Edition 02/2006, A5E00273194-02
Windows Automation Center, WinAC Slot Version 4.0
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