- Password protection;
a password concept protects the user program from unauthorized access. - Diagnostics buffer;
the last 500 errors and interrupt events are saved in a buffer for diagnostic purposes. - Maintenance-free data back-up;
all standard data is automatically written onto the SIMATIC Micro Memory Card by the CPU if there is a voltage interruption, and is available unchanged following voltage recovery.
Parameterizable properties
The S7 configuration as well as the properties and response of the CPUs can be parameterized using STEP 7:
- MPI multi-point interface;
determining station addresses - Restart/cycle time behavior;
stipulation of maximum cycle time and loading as well as self-test functions - Clock memory;
setting of addresses - Protection level;
specifying the access rights to program and data - System diagnostics;
determining handling and scope of the diagnostic alarms - Watchdog interrupts;
setting of periodicity - Clock interrupts;
setting of start date, start time and periodicity - PROFIBUS DP master/slave interface;
user-defined address assignment for distributed I/O
Display and information functions
- Status and error indications;
LEDs indicate hardware, programming, time or I/O errors, and operating statuses such as RUN, STOP and start-up. - Test functions;
the PG is used to indicate signal status during program execution, to modify process variables independently of the user program and to output the contents of stack memories. - Information functions;
you can use the PG to obtain information about the storage capacity and operating mode of the CPU , the current utilization of the main and load memories as well as current cycle times and diagnostic buffer contents in plain text.
Integrated communication functions
- PG/OP communication
- Global data communication
- S7 basic communication
- S7 communication (server only)
- Routing
- Data block routing
Communication
The safety-related and standard communication between the central controller and the distributed stations is performed via PROFIBUS DP. The specially developed PROFIBUS profilePROFIsafe allows user data for the safety function to be transferred within the standard data message frame. Additional hardware components, such as special safety buses, are not necessary. The necessary software is either integrated in the hardware components as an expansion of the operating system or it is loaded into the CPU as a certified software block.
System functions
The CPU provides many extensive system functions for diagnostics, parameterization, synchronization, alerting, time measurement, etc.
For further details, see the manual.
Mode of operation
The safety functions of the F-CPU are included in the F program of the CPU and in the fail-safe signal modules.
The signal modules monitor the input and output signals through discrepancy analyses and the application of test signals.
The CPU checks that the controller is operating correctly by means of periodic self-tests, test instructions as well as logical and time-based program execution checks. The I/O is checked with requests for a sign of life.
If an error is diagnosed in the system, it is transferred to a safe state.
An F runtime license is not required for operating the S7-300F-2 DP.
Programming
The S7-300F is programmed in the same manner as the other SIMATIC S7 systems. The user program for non fail-safe system components is created using the familiar programming tools, e.g. STEP 7.
SIMATIC S7 Distributed Safety option package
The STEP 7 option package "SIMATIC S7 Distributed Safety" is required for programming the safety-related program sections. The package contains all the functions and blocks required to create the F program.
The F program with the safety functions is created in F-FBD or F-LAD or using special function blocks from the F library. Use of F-FBD or F-LAD simplifies configuration and programming of the plant and, due to the cross-plant, uniform presentation, also acceptance testing. The programmer can therefore concentrate entirely on configuring the safety-related application, without the need to use any additional tools.