Detailed description
2.6 Interface structure
Power Line Basic PLC Program (P3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
2-37
Machine operation
All operator inputs, which lead to response actions on the machine, are monitored by the
PLC. Operator actions are usually performed on the machine control panel. However, it is
also possible to perform some operator actions on the MMC (e.g., mode selection, INC
mode selection).
The PLC operating system enters the operating signals sent by the MMC directly into the
interface data blocks. In standard cases, the basic program, which decodes the operating
signals, allows the operator actions to be performed on the machine control panel (provided
the operator actions are available) or on the MMC. If required, the user can switch off the
operation via MMC through a parameter "MMCToIF" of FB1.
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 status list. Communication events and I/O module diagnostics data (for
modules with diagnostic functions) are also entered.
• Diagnostics events, which lead to a system stop, are also entered with a time stamp in a
diagnostic buffer (circular buffer) in the chronological order of their occurrence.
• The events entered in the diagnostic buffer are automatically transmitted to
human machine interface systems (OS or MMC) via the MPI or via the OPI through the
COM module, 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 is executed by the MMC software.
• An SFC (system function call) can also be used by the user program to enter messages
in the diagnostic buffer.
• The events are entered in the diagnostic buffer in coded format.
The associated message texts must be stored on the OP or MMC.
An FC (FC10) for message acquisition is prepared in conjunction with the basic program.
This FB records events, subdivides them into signal groups and reports them to the MMC via
the diagnostic 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)
with bit fields for user messages.
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