Siemens SINUMERIK 840D sl Function Manual page 844

P3: Basic PLC program for SINUMERIK 840D sl
13.9 Interface structure
The message acquisition structure is shown in the figure "Acquisition and signaling of PLC
events". The features include:
● Bit fields for events related to the NC/PLC interface are combined in a single data block
(DB2) with bit fields for user messages.
● Bit fields are evaluated at several levels by FC10.
– Evaluation 1; acquisition of group signals
– Evaluation 2; acquisition of alarm messages
– Evaluation 3; acquisition of operating signals
● The scope of the user bit fields (user area) is set by default to 10 areas with 8 bytes each,
but the number of areas can also be adjusted to suit the requirements of the machine
manufacturer via basic program parameters in FB1.
Acknowledgement concept
The following acknowledgement procedures are implemented for error and operational
messages:
Operating messages are intended for the display of normal operating states as information for
the user. Acknowledgement 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 up-to-date log of existing operating messages using the identifiers "operating
message arrived" and "operating message gone".
Alarm messages 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 alarm 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 "Alarm gone". This enables the HMI to also maintain
an up-to-date log of pending alarm 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.
844
A group signal is generated for each group of signals if at least one bit signal is set to
"1". This signal is generally linked to the disable signal of the NC/PLC interface (on
modules with diagnostic functions). The group signals are acquired completely in cycles.
A fixed specification exists to define which signals in a group generate an alarm message
when they change from "0" to "1".
A fixed specification exists to define which signals in a group generate an operational
message.
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions