Siemens SINUMERIK 840D sl Function Manual page 1314

Detailed description
2.6 Interface structure
Acknowledgment concept
The following acknowledgment procedures are implemented for error and operational
messages:
Operating messages are intended for the display of normal operating states as information
for the user. Acknowledgment signals are, therefore, not required for this type of message.
An entry is made in the diagnostic status list for incoming and outgoing messages. The HMI
maintains an uptodate log of existing operating messages using the identifiers "operating
message arrived" and "operating message gone".
Interrupt messages are used to display error states on the machine, which will usually lead
to the machine being stopped. Where several errors occur in rapid succession, it is important
to be able to distinguish their order of occurrence for troubleshooting purposes. This is
indicated, on the one hand, by the order in which they are entered in the diagnostic buffer
and on the other, by the time stamp, which is assigned to every entry.
If the cause of the error disappears, the associated interrupt message is only deleted if the
user has acknowledged it (e.g. by pressing a key on the MCP). In response to this signal, the
"Message acquisition" FC examines which of the reported errors have disappeared and
enters these in the diagnostic buffer with the entry "Interrupt gone". This enables the HMI to
also maintain an uptodate log of pending interrupt messages. The time of day indicating the
time at which the error occurred is maintained for messages, which are still pending (in
contrast to a received interrogation).
STEP 7
A tool can be started in the SIMATIC Manager via menu item Target system > CPU
messages. Alarms and messages can be displayed by number using this tool. To do this,
acivate the "Alarm" tab and enter a check mark under "A" in the upper half of the screen.
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Basic logic functions: PLC basic program solution line (P3 sl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0