Error Diagnostics - Siemens SIMATIC S7 Equipment Manual

Operation
5.4

Error Diagnostics

Diagnostics
Diagnosis alarm
5-8
Diagnostics acquire errors on the module
Diagnosis information is updated continuously and stored in the diagnosis
area of the dual port RAM. If channel-related diagnostics is enabled, this
additional information is entered when channel errors occur. Both arriving
and departing errors are considered by the diagnostics.
The CPU can read out the diagnosis area. An error which has occurred is
indicated by the red "SF" LED regardless of whether the diagnosis alarm is
enabled or not.
Note
This alarm is not forwarded to the CPU unless the diagnosis alarm is en-
abled.
If the diagnosis alarm has been enabled during assignment of the SM 338
parameters, an OB 82 must exist in the programmable controller. The first
six words of the local data of OB 82 contain information concerning the
module address and identifier, and the four bytes of system diagnostics.
When a diagnosis alarm is received, the CPU branches to OB 82 and trans-
fers the diagnosis information to the user program.
SM 338 Equipment Manual
(4) J31069-D401-U1-A0-7618