Siemens SINUMERIK 840D sl Function Manual page 1313

PLC messages
The signaling functions are based on the system diagnostic functions integrated in the
operating system of the AS 300. These have the following characteristics:
• The PLC operating system enters all important system states and state transitions in a
• Diagnostics events, which lead to a system stop, are also entered with a time stamp in a
• The events entered in the diagnostic buffer are automatically transmitted to
• The PLC user program can also use SFCs (System Function Calls) to enter messages in
• The events are entered in the interrupt buffer.
An FC (FC 10) for message acquisition is prepared in conjunction with the basic program.
This FC records events, subdivides them into signal groups and reports them to the HMI via
the interrupt buffer.
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 VDI interface are combined in a single data block (DB2)
• Bit fields are evaluated at several levels by FC10.
• The scope of the user bit fields (user area) is set by default to 10 areas with 8 bytes each,
Basic logic functions: PLC basic program solution line (P3 sl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
diagnostics status list. Communication events and I/O module diagnostics data (for
modules with diagnostic functions) are also entered.
diagnostic buffer (circular buffer) in the chronological order of their occurrence.
human machine interface systems (OP or HMI) via the bus systems once these have
issued a ready signal (message service). Transfer to the node ready is a function of the
PLC operating system. Receipt and interpretation of the messages are executed by the
HMI software.
the diagnostic buffer or ALARM S/ALARM SQ buffer.
The associated message texts must be stored on the OP or HMI.
with bit fields for user messages.
– Evaluation 1; Acquisition of group signals
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 VDI interface (on
modules with diagnostic functions). The group signals are acquired completely in
cycles.
– Evaluation 2; Acquisition of interrupt messages
A fixed specification exists to define which signals in a group generate an interrupt
message when they change from "0" to "1".
– Evaluation 3; Acquisition of operating signals
A fixed specification exists to define which signals in a group generate an operational
message.
but the number of areas can also be adjusted to suit the requirements of the machine
manufacturer via basic program parameters in FB 1.
Detailed description
2.6 Interface structure
39