The log is the common mechanism for errors, warnings and debugging information to be reported to the user.
There are three functions, one for each of the above, all with the
arguments. The first argument is the logging level, a number between 1
9 indicating the severity of the condition - see below. The remaining
arguments are interpreted as the arguments to a
void plc_log_trcmsg(int min_debug_level, const char *format, ...);
void plc_log_wrnmsg(int min_debug_level, const char *format, ...);
void plc_log_errmsg(int min_debug_level, const char *format, ...);
Note that the PLC or the module that experienced the error does not necessarily have to stop executing (or crash), but may continue with other actions (e.g. modbus_tcp module cannot connect to a remote host 1 to read point A, but continues to connect to host 2 to get point B).
The default logging level is 1, which should be used by any part of the program to log messages that one would like to see by default. Typically, levels 2..5 will be used only by module specific code, while levels 6..9 will be used by the MatPLC libraries; however, it really depends on the severity of the event rather than its source.
The following table contains examples of the kinds of events that should be logged at each level.
All messages logged by the library or by generic and specific
modules (that is, anything included with MatPLC itself) should be
listed in the Log messages appendix.
$Date: 2005/12/08 09:24:46 $