S7-300

General

The S7-300 automation system is modular in design. It has a comprehensive range of modules that can be combined individually.

A system includes the following:

• A CPU:
  Different CPUs are available for different performance ranges, including CPUs with integral inputs/outputs and the corresponding functions, as well as CPUs with integral PROFIBUS DP, PROFINET and point-to-point interfaces.
• Signal modules (SMs) for digital and analog inputs/outputs.
• Communications processors (CPs) for bus connection and point-to-point connections.
• Function modules (FMs) for high-speed counting, positioning (open-loop/closed-loop) and PID control.

The following can also be used depending on requirements:

• Load power supply (PS) for connecting the SIMATIC S7-300 to a supply voltage of 120/230 V AC.
• Interface modules (IMs) for connecting the central controller (CC) and expansion units (EUs) in multi-tier configurations.
  The SIMATIC S7-300 can be operated with up to 32 modules distributed across the CC and 3 EUs. All modules can be operated in enclosures and without fans.
• SIPLUS modules for extended environmental conditions:
  suitable for temperature range -25 to +60 °C, and higher humidity, condensation and frost loads. Can be used direct on vehicles or outside building in an IP20 cabinet protected against direct sunlight and rainwater/spray water. Air-conditioned cabinet and IP65 housing not required.

Design

Simple design makes the S7-300 flexible and service-friendly:

• Module mounting:
  Simply hang the modules on the mounting rail, swing them into place and screw into position.
• Integral backplane bus:
  The backplane bus is integrated into the modules. The modules are connected via bus connectors plugged into the rear of the housings.
• Simple replacement of the modules with mechanical key coding:
  Only the fixing screw of the modules has to be unscrewed to replace the module. Wired front connectors are easy to release by pressing on the locking mechanism. The front connector coding prevents connection of the wired front connector to the wrong module type.
• Field-proven connections:
  Screw-type, spring-loaded or insulation-displacement front connectors are offered for the signal modules.
• TOP Connect:
  This offers pre-assembled wiring with 1-core to 3-core connections and screw-type or spring-loaded terminals. Alternative to wiring direct on the signal module.
• Defined installation depth:
  All connections and connectors are recessed into the modules and protected and covered by front doors. All modules thus have a defined installation depth.
• No slot rules:
  Signal modules and communications processors can be connected in any way without restrictions. The system configures itself.

Expansion

If users require more than 8 slots SM, FM or CP modules for their automation tasks, the S7-300 (except CPU 312 and CPU 312C) can be expanded:

• Max. 32 modules on CC and 3 EUs:
  In total, a maximum of 3 expansion units (EUs) can be connected to the central controller (CC). Eight modules can be connected to each CC/EU.
• Connection via interface modules:
  Each CC/EU has its own interface module. It is always plugged into the slot next to the CPU on the CC, and it handles communication with the EUs autonomously.
  • Expansion via IM 365:
    1 EU, distance max. 1 m; supply voltage is also transferred.
  • Expansion via IM 360/361:
    3 EUs, max. distance between CC and EU and between EU and EU, 10 m in each case.
• Physically separate installation:
  The individual CCs/EUs can also be installed at greater distances from each other. Distance between two neighboring CC/EU or EU/EU: max. 10 m.
• Flexible mounting options:
  The CCs/EUs can be mounted horizontally or vertically. They can thus adapt optimally to the available space.

Communication

The S7-300 has different communication interfaces:

• Communications processors for connecting to the bus systems AS-Interface, PROFIBUS and PROFINET/Industrial Ethernet.
• Communications processors for point-to-point connections.
• Multipoint interface (MPI ), integrated into the CPU;
  the low-cost solution for simultaneous connection of PGs/PCs, HMI systems and other SIMATIC S7/C7 automation systems.

Process communication via PROFIBUS DP

The SIMATIC S7-300 is connected to the PROFIBUS DP bus system via a communications processor or the CPUs with integral PROFIBUS DP interface. The CPUs with PROFIBUS DP master/slave interface enable distributed automation configurations with high speed and simple handling.

The distributed I/O via PROFIBUS DP is treated just like a centralized I/O from the user's perspective (same configuring, addressing and programming).

The following can be connected as masters:

• SIMATIC S7-300
  (via CPUs with PROFIBUS DP interface or PROFIBUS DP CPs)
• SIMATIC S7-400
  (via CPUs with PROFIBUS DP interface or PROFIBUS DP CPs)
• SIMATIC C7
  (via C7 with PROFIBUS DP interface or PROFIBUS DP CPs)
• SIMATIC S5-115U/H, S5-135U and S5-155U/H with IM 308
• SIMATIC 505

For performance reasons, no more than 2 masters must be connected on one line.

The following can be connected as slaves:

• ET 200 distributed I/O devices
• S7-300 via CP 342-5
• CPU 313C-2 DP, CPU 314C-2 DP, CPU 314C-2 PN/DP, CPU 315-2 DP, CPU 315-2 PN/DP, CPU 317-2 DP, CPU 317-2 PN/DP and CPU 319-3 PN/DP
• C7-633/P DP, C7-633 DP, C7-634/P DP, C7-634 DP, C7-626 DP, C7-635, C7-636
• Field devices

Although PG/PCs with STEP 7 or OPs are masters on the bus, they only use the MPI functions that also run in part via PROFIBUS DP.

Process communication via PROFINET IO

The SIMATIC S7-300 is connected to the PROFINET IO bus system via a communications processor or the CPUs with integral PROFINET interface. The CPUs with PROFINET interface enable distributed automation configurations with high speed and simple handling.

The distributed I/O via PROFINET IO is treated just like a centralized I/O from the user's perspective (same configuring, addressing and programming).

The following can be connected as IO controllers:

• SIMATIC S7-300
  (via CPUs with PROFINET interface or PROFINET CPs)
• SIMATIC ET 200
  (via CPUs with PROFINET interface)
• SIMATIC S7-400
  (via CPUs with PROFINET interface or PROFINET CPs)

The following can be connected as IO devices:

• ET 200 distributed I/O devices
• ET 200S IM151-8 PN/DP CPU, ET 200pro IM154-8 PN/DP CPU
• SIMATIC S7-300
  (via CPUs with PROFINET interface or PROFINET CPs)
• Field devices

Process communication via AS-Interface

The S7-300 has a suitable communications processor (CP 342-2) for connecting field devices (AS-Interface slaves) for the AS-Interface-Bus.

For additional information, see Communications processors.

Data communication via CP or integral interface (point-to-point)

Point-to-point connections can be conveniently and at low cost via the CP 340/CP 341 communications processors or the integral interface of the CPU 313C-2 PtP or CPU 314C-2 PtP. Different protocols with the three physical transmission media are available:

• 20 mA (TTY) (CP 340/CP 341 only)
• RS 232C/V.24 (CP 340/CP 341 only)
• RS 422/RS 485

The following can be connected:

• SIMATIC S7 and SIMATIC S5 automation systems and non-Siemens systems
• Printers
• Robot controls
• Scanners, barcode readers, etc.

Special blocks are included in the scope of supply of the manuals for the communication functions.

Data communication via multipoint interface (MPI)

The multipoint interface (MPI) is a communication interface integrated into the CPUs of the SIMATIC S7-300. It can be used for simple networking.

• The MPI enables simultaneous connection of several PGs/PCs with STEP 7, HMI systems (OP/OS), S7-300 and S7-400.
• Global data:
  With the "Global data communication" service, networked CPUs can exchange data with each other cyclically. An S7-300 CPU can exchange up to 4 packets of 22 bytes each, with a maximum of 16 CPUs participating in the data exchange (with STEP 7 V4.x).
  This allows, for example, one CPU to access the inputs/outputs of another CPU. Global data communication can only take place via the MPI interface.
• Internal communications bus (C bus):
  The MPI of the CPU is connected direct with the C bus of the S7-300. FM/CP modules with C bus connection can thus be addressed direct from the PG via the MPI.
• Powerful communications technology:
  • Up to 32 MPI nodes.
  • Several communication connections per CPU for S7 basic communication with the SIMATIC S7-300/-400.
  • Several communication connections per CPU for S7 communication with PGs/PCs, SIMATIC HMI systems, and the SIMATIC S7-300/400.
  • Data transfer rate 187.5 kbit/s or 12 Mbit/s
• Flexible configuration options:
  Field-proven components are used to establish MPI communication: Bus cable, bus connectors and RS 485 repeaters from the PROFIBUS and "distributed I/O" ranges. They enable optimal adaptation of the design to the requirements. For example, up to 10 repeaters can be switched in series to bridge larger distances between any two MPI nodes.

Data communication via CP

The SIMATIC S7-300 can be connected to the PROFIBUS and Industrial Ethernet bus systems via the CP 342 and CP 343 communications processors.

The following can be connected:

• SIMATIC S7-300
• SIMATIC S7-400
• SIMATIC S5-115U/H, S5-135U, S5-155U/H
• Programming devices
• Personal computers
• SIMATIC HMI human machine interface systems
• Numerical controllers
• Robot controls
• Industrial PCs
• Drive controls
• Devices of other manufacturers

S7-300F

The S7-300F can be operated with two I/O designs:

• Design with I/O in ET 200M:
  Fail-safe digital/analog input and output modules for centralized or distributed use (Cat.4/SIL3 only in conjunction with isolating module).
• Design with I/O in ET 200S PROFIsafe:
  Fail-safe digital input and output modules for distributed use