Programming manual M238 | 3 MB - BERGER - POSITEC

Error Detection, Types, and Management
Detected Error Management
The controller manages 3 types of detected errors:
external detected errors
application detected errors
system detected errors
Controller States and Behaviors
The following table describes the types of errors that may be detected:
Type of
Error
Detected
External
Error
Detected
Application
Error
Detected
System
Error
Detected
Description Resulting
Controller
State
External errors are detected by the system while RUNNING or
STOPPED but do not affect the ongoing controller state. An
external error is detected in the following cases:
The controller is configured for an expansion module that
is not present or not detected
The boot application in Flash memory is not the same as
the one in RAM.
An application error is detected when improper programming
is encountered or when a task watchdog threshold is
exceeded.
Examples:
task (software) watchdog exception
execution of an unknown function
etc.
A system error is detected when the controller enters a
condition that cannot be managed during runtime. Most such
conditions result from firmware or hardware exceptions, but
there are some cases when incorrect programming can result
in the detection of a system error, for example, when
attempting to write to memory that was reserved during
runtime.
Examples:
System (hardware) watchdog overflow
exceeding the defined size of an array
etc.
RUNNING with
External Error
Detected
Or
STOPPED
with External
Error Detected
NOTE: refer to the M238 PLCSystem Library Guide (see Modicon M238 Logic
Controller, System Functions and Variables, M238 PLCSystem Library Guide) for
more detailed information on diagnostics.
EIO0000000384 04/2012 63
HALT
BOOTING →
EMPTY