Structures

StrExtArgs_typ

Format arguments for a log message. This type comes from StringExt and is passed to the log functions by address through pMsgData. Each format specifier in the message consumes the next unused member of the matching type, in order.

Application variables are left undeclared in this snippet. The call is guarded on an edge flag because a log entry is a one-shot event, not something to write every scan.

void _CYCLIC ProgramCyclic(void)
{
	StrExtArgs_typ msgData;

	if (partCompleteEdge) {
		memset(&msgData, 0, sizeof(msgData));

		msgData.i[0] = partCount;
		msgData.s[0] = (UDINT)recipeName;

		logInfo("App", 1, "Produced %i parts on recipe %s", (UDINT)&msgData);
	}
}

A specifier past the fifth of its type is dropped from the rendered message without an error.

LOG_PERSISTENCE_enum

Where a logbook’s entries are stored. Selected when the logbook is created with createLogInit().

LOG_PERSISTENCE_PERSIST is the usual choice. Log entries earn their keep after a restart, which is exactly when a volatile logbook is already empty.

Note: For the remanent and persistent options, entries are held in a DRAM image that is copied to the backing memory every 60 seconds and on an orderly shutdown. Up to a minute of entries can be lost to a power fail or watchdog reset.

LOG_SEVERITY_enum

Severity of a log entry. The severity-specific functions select this internally; it is exposed for code that builds its own event IDs. Values align with the arEVENTLOG_SEVERITY_ constants.

Status

Every LogThat function returns a status. 0 means the operation succeeded.

Any other non-zero value is passed straight through from the underlying ArEventLog function block that failed, so arEVENTLOG_ERR_ codes show up here. These are the ones that come up in practice:

See the Automation Studio help for ArEventLog for the full list.

Note: Versions before 0.05.0 wrapped the BRSE_ARL library and could return its 58200-58203 codes. Those are no longer produced.

Constants

logLogger_typ

Legacy type from the ManageLoggers() interface that was removed in 0.05.0. It is still exported for compatibility with older code, but no LogThat function uses it.