104
CP 343−2 / CP 343−2 P AS−Interface Master
Release 08/2008
C79000−G8976−C149−04
6
Diagnostics and Interrrupts of the CP 343-2
In the protected mode, the CP 343-2 signals a diagnostic interrupt whenever the
configuration on the AS-Interface is changed. Changes in the configuration might
be that voltage on the AS-Interface is too low (AS-i Power Fail) or that
configuration errors have been detected (missing, incorrect or existing but
unconfigured AS-i slaves).
6.1
Overview
If the CP 343-2 detects an external or internal fault/error (AS-i slave failures,
EEPROM error on the CP, ...) during operation, it signals this by triggering a
diagnostic interrupt on the S7 I/O bus.
The S7 CPU then interrupts the cyclic user program (OB1), enters the event as
“module fault” in the system diagnostic buffer and behaves as follows:
S
If the user has not programmed a suitable interrupt OB (OB82), the PLC CPU
changes to the STOP mode!
S
If the user has programmed OB 82, this is started by the PLC operating
system. The local data of OB 82 already provides the user with a certain
amount of diagnostic information. (Which module triggered the interrupt. What
type of error has occurred ...). The user program can obtain more detailed
information (which slave has failed? ...) by reading the diagnostic data record
DS 1 using the system functions SFC 51 (”RDSYSST”) or SFC 59 (”RD_REC”).
When OB82 has been executed, the PLC continues the cyclic program (OB1)
at the point at which it was interrupted.
Note
OB82 cannot be programmed on the CPU 312; in other words, if a diagnostic
interrupt occurs, the CPU changes to the STOP mode.
6.2
Interrupt Events
The CP 343-2 distinguishes between interrupt events entering and leaving the
state. If the occurrence of an interrupt event leads to an error-free status, a
diagnostic interrupt leaving state is triggered (in OB 82: Bit OB82_MDL_DEFECT
= 0). All other interrupt events result in a diagnostic interrupt entering state (Bit
OB82_MDL_DEFECT = 1).
The following events can lead to a diagnostic interrupt being triggered by the CP
343-2: