Error Evaluation In The User Program - Siemens SIMATIC FM 351 Manual

11.5

Error Evaluation in the User Program

In your user program, you can plan specific reactions to errors. The following data
are available for this purpose:
The return values (RET_VAL) of the linked standard FCs:
This value is refreshed each time the block is called.
RET_VAL = –1 is a group indicator for a synchronous error in a job or in the
communication of the module.
Each job has an error bit (_ERR) as a group indicator for an error in the job or
in one of its predecessors in a chain of jobs:
The error bit is set for a write job and for the subsequent jobs if a data error was
indicated by the module or if a communication error occurred.
In read jobs, the error bit is set for the job affected if a communication error
occurred.
The error bits are set again by FC ABS_CTRL after a job has been executed.
They should be reset however by the user program to allow error evaluation.
The return signal DATA_ERR is a group indicator for an error detected by the
module in a write job. The signal is updated with the next write job.
The return signal OT_ERR (operator error) is used as a group indicator for an
error detected by the module when a travel operation is started. The error must
be acknowledged after it has been eliminated by setting OT_ERR_A=1.
The return signal DIAG is set when the content of the diagnostic buffer
changes. This signal can come later than the signals DATA_ERR and
OT_ERR.
The communication error JOB_ERR contains an error code for a
communication problem between the FC and module (refer to the list of
JOB_ERR messages in Appendix C.4). The value is updated after a job has
been executed and stored by FC ABS_CTRL in the channel DB and by FC
ABS_DIAG in the diagnostic DB.
FC ABS_DIAG for reading out the diagnostic buffer of the module. Here, you
can find out the causes of errors for synchronous and asynchronous events.
Diagnostic interrupts for fast reaction to events in the diagnostic interrupt OB
(OB82).
Figure 11-3 shows a possible program structure with which you can react to the
return signals "Data Error" (DATA_ERR), "Operator Error" (OT_ERR) and the error
bits of the jobs (_ERR).
FM 351 Positioning Module
C79000-G7076-C351-02
Diagnostics
11-5