S7-300

A host of features support users in programming, commissioning and servicing the S7-300.

• High-speed instruction processing:
  Instruction execution times from 4 ns open up completely new application options in the low-end and mid performance range.
• Floating-point arithmetic:
  With floating-point arithmetic, even complex arithmetic functions can be used effectively.
• User-friendly parameter assignment:
  There is only one single software tool with a uniform operator interface for parameterizing all modules. This saves on induction and training overhead.
• Human machine interfacing (HMI):
  User-friendly HMI services are already integrated into the operating system of the S7-300. Costly programming of these functions is no longer necessary: The SIMATIC HMI system requests process data from the SIMATIC S7-300 — the S7-300 transfers this data at the desired update times. The operating system of the SIMATIC S7-300 handles the transfer autonomously. And all with uniform symbols and database.
• Diagnostics functions:
  The intelligent diagnostics system of the CPUs continuously checks the functionality of the system and registers faults and specific system events (e.g. time errors, module failure, etc.). The events are stored in a ring buffer and time-stamped for future troubleshooting.
• Password protection:
  Password protection allows users to protect their know-how effectively against unauthorized copying and modification.

The SIMATIC S7-300 complies with national and international standards:

• CE mark
• UL approval
• CSA approval
• cULus approval
• cULus HAZ.LOC. approval
• FM approval
• ATEX approval
• Marking for Australia
• IEC 61131
• Marine approval
  • ABS (American Bureau of Shipping)
  • BV (Bureau Veritas)
  • DNV (Det Norske Veritas)
  • GL (Germanischer Lloyd)
  • LRS (Lloyds Register of Shipping)
  • Class NK (Nippon Kaiji Kyokai)

For details, refer to Manual "SIMATIC S7-300 Programmable Controller S7-300 Module Data" under "1. General technical data / 1.1 Standards and approvals".

Communication

The CPUs of the SIMATIC S7-300 support the following communication types:

• Process communication:
  For cyclic addressing of I/O modules (exchange of the process image) via a bus (AS-Interface, PROFIBUS DP or PROFINET). Process communication is called up from the cyclic execution levels.
• Data communication:
  For data exchange between automation systems or between HMI stations and several automation systems. Data communication takes place cyclically or it is called from the user program via blocks on an event-driven basis.

The user-friendly STEP 7 operator interface that significantly simplifies configuring is available to users for configuring the communication functions.

Data communication

The SIMATIC S7-300 has different data communication mechanisms:

• Cyclic exchange of data packets between CPUs networked via MPI with global data communication.
• Event-driven communication with other partners with the communication functions. Networking can take place via MPI, PROFIBUS or PROFINET.

Global data

With the "Global data communication" service, networked CPUs can exchange data with each other cyclically (max. 8 GD packets with 22 bytes each per cycle). This allows, for example, one CPU to access the data, bit memories and process image of another CPU. Global data communication can only take place via the MPI. Configuring is carried out using the GD table in STEP 7.

Communication functions

Communication services with S7/C7 partners can be established with system-integrated blocks.

The services are:

• S7 basic communication via MPI.
• S7 communication via MPI, C bus, PROFIBUS and PROFINET/Industrial Ethernet.
  The S7-300 can be used:
  • as a server via MPI, C bus and PROFIBUS
  • as a server or client via the integral PROFINET interface

Communication services with S5 partners and non-Siemens devices can be established with reloadable blocks.

The services are:

• S5-compatible communication via PROFIBUS and Industrial Ethernet.
• Standard communication (non-Siemens systems) via PROFIBUS and Industrial Ethernet.

In contrast to global data, communication connections must be set up for the communication functions.

Integration into the IT world

The S7-300 makes it possible to simply link the modern IT world with automation engineering. The following IT functions are possible via the CP 343-1 Advanced:

• IP routing;
  forwarding of IP V4 messages from the Gigabit to the PROFINET interface controlled via the IP access list
• WEB server;
  up to 30 MB of freely definable HTML pages can be called up via a standard browser; data handling of your own file system via FTP
• Standard diagnostics pages;
  for high-speed diagnostics in the plant for all modules plugged into the mounting rack, without additional tool
• E-mails;
  Sending of e-mails with authentication direct from the user program. The e-mail client function makes it possible to alert users direct from the control program
• Communication via FTP;
  open protocol available on most operating system platforms
• The 30 MB RAM file system can be used for intermediate storage of dynamic data.

The S7-300 PROFINET CPUs have an integral Web server. Information can thus be read out of the S7-300 station using a standard Web browser:

• General CPU information
• Content of the diagnostics buffer
• Variable table
• Tag status
• Module status
• Alarms
• Information on Industrial Ethernet
• Topology of the PROFINET nodes

Via the user-defined pages, write access via the Web server to the S7-300 CPU is also possible.

Isochronous mode

The system function isochronous mode enables synchronous coupling

• of the distributed signal acquisition,
• the signal transmission via PROFIBUS/PROFINET and
• the program execution

for the PROFIBUS/PROFINET constant bus cycle time.

An automation solution is created that captures and processes the input signals and outputs output signals at constant intervals (constant bus cycle time). A consistent partial process image is created at the same time.

By means of constant bus cycle times and synchronous signal processing of the distributed I/O, the S7-300 ensures precisely reproducible and defined process response times.

An extensive range of components that support the isochronous mode system function is available for handling demanding tasks from the areas of motion control, measured value acquisition, high-speed controls, etc.

In distributed automation solutions, the SIMATIC S7-300 now also opens up the important application area of high-speed processing operations and enables the achievement of maximum precision and reproducibility. This means increased production with optimal and constant quality.

Diagnostics and process monitoring of modules

Many input/output modules of the SIMATIC S7-300 have intelligent capabilities:

• Monitoring of signal acquisition (diagnostics).
• Monitoring of signals from the process (hardware interrupt).

Diagnostics

Diagnostics can be used to determine whether signal acquisition (in the case of digital modules) or analog processing (analog modules) of the module is functioning fault-free. In diagnostics analysis, a distinction must be made between parameterizable and non-parameterizable diagnostics messages:

• Parameterizable diagnostics messages:
  The diagnostics message is only sent if it has been enabled by the appropriate parameterization.
• Non-parameterizable diagnostics messages:
  These messages are sent as a matter of course, that is, independently of parameterization.

If a diagnostics message is active (e.g. "No sensor supply”), the module triggers a diagnostics interrupt (if the diagnostics message is parameterized, only after the appropriate parameterization). The CPU interrupts processing of the user program or low priority classes, and processes the relevant diagnostics interrupt block (OB 82).

Hardware interrupt

Process signals can be monitored via hardware interrupts and responses to changes in the signals can be triggered.

• Digital input modules:
  Depending on the parameterization, the module can trigger a hardware interrupt for each channel group optionally at a rising edge, a falling edge or at both edges of a signal status change. The CPU interrupts processing of the user program or low priority classes, and processes the relevant diagnostics interrupt block (OB 40). The signal module can buffer one interrupt per channel.
• Analog input modules:
  A working range is defined by parameterizing an high and low limit value. The module compares the digitized measured value with these limits. If the measured value violates one of these limits, a hardware interrupt is triggered. The CPU interrupts processing of the user program or low priority classes, and processes the relevant diagnostics interrupt block (OB 40). If the limits are above/below the overrange/underrange, no comparison is made.
  

S7-300F

Mode of operation

The safety functions of the S7-300F are contained in the F program of the CPU and in the fail-safe signal modules.

The signal modules monitor output and input signals by means of discrepancy analyses and test signal injections.

The CPU checks the proper operation of the controller with regular self-tests, command tests, and logical and chronological program execution checks. In addition, the I/O is checked by means of sign-of-life requests.

If a fault is diagnosed in the system, the system is brought to a safe state.

Programming

The safety-related programs for the CPU 315F are programmed with the STEP 7 languages LAD and FBD. The scope of functions with regard to operations and data types is restricted here. A safety-related program is created by making special specifications at the compiling stage. As well as the fail-safe program, a standard program can also run in parallel on one CPU (coexistence) with no restrictions.

An additional component part of this software package is the F library with off-the-shelf, TUV-accepted programming examples for safety-related functions. These programming examples can be modified but the modifications must be re-certified.

S7 F Distributed Safety option package

The option package "S7 F Distributed Safety" is required for programming the safety-related program sections. The package contains all the necessary functions and blocks for creating the F program. STEP 7 from V5.1SP3 must be installed for S7 F Distributed Safety to run.