Introducing PLC Siemens S7-300
The S7-300 is designed as a multi-module system linked together. Each module is an individual device, with independent functions that, when combined with a programmable controller, form an operating system of the s7-300.
So what equipment does this system include?
- CPU: There are different types of CPU, depending on the large or small application, the user will choose the CPU with the corresponding programmability and performance. There are independent CPUs that are only used to store control programs, and there are compact CPUs with built-in digital and analog input and output signals. There are simple CPUs that only integrate MPI interfaces, and more complex ones that integrate both Profibus DP and Profinet interfaces on the PLC body.
- Signal module (SM) digital and analog input/output.
- Communication processor (CP).
- Function (FM) modules for high-speed counting, positioning (open loop/closed loop) and PID control.
- The power supply (PS) converts AC voltage (120v/230v) to a 24V DC electrical signal that feeds the PLC.
- Expansion communication modules (IMs) to connect the central control unit (CC) to other extension stations (EUs)
- SIMATIC S7-300 can be operated with up to 32 modules mounted on CC and expandable to 3 EUs.
- SIPLUS modules for extreme environmental conditions
Design Siemens S7-300 PLC
The S7-300 system is designed to be simple, flexible and easy to maintain:
- Rail – module: Before installing s7-300 we must fix the rail of this device.
Then simply place the module in the correct position and hang it on the rail, turning the screw to fix it. - Connect modules via backplane
There is a small connecting device called a backplane mounted behind the housing of each module to connect the modules of the s7-300 together. - Mechanical mechanism for easy replacement: The module is fixed to the rail via a locking screw, when it needs to be replaced, just open the locking screw.
Each module will have an attached accessory called a front-connector used for wiring – supplying electrical signals to the module. This front-connector is designed with a push-to-open mechanism for easy mounting and dismounting of the module. - Wiring for the module: Through the front-connector, the signal wire is connected to the device module via a screw mechanism or push-in mechanism (push to open and lock).
- Connect the signal wire to the far: One of the convenience features of this device is the built-in wiring mechanism. Siemens provides a set of pre-wiring connectors for mounting on the module and connecting to remote devices (depending on the length of the wiring harness).
- Installation depth: All connections and wires are recessed into the modules and protected, covered by front covers.
- No position rule: Signal modules and communication processors can be connected in any way without location restrictions.
Communication of Siemens S7-300 PLC
The S7-300 has various communication methods:
- Communication modules for point-to-point connections.
Multipoint Communication Protocol (MPI) is built into all CPUs of the s7-300; low cost solution for simultaneous connection of PG/PC, HMI systems and other SIMATIC S7/C7 automation systems. - This is the old way of communication before the advent of PROFINET.
- AS-Interface, PROFIBUS and PROFINET/Industrial Ethernet communications. In case the CPU does not have a built-in, users can purchase additional communication modules to communicate with other peripheral devices.
Application of Siemens S7-300
SIMATIC S7-300 is a mini PLC system for medium-sized applications.
Application areas of SIMATIC S7-300 include:
- Special machines
- Looms
- Packing machine
- Manufacture of mechanical equipment in general
- Control building
- Manufacture of machine tools
- Installation system
- Electrical / Electronic Industry and Skilled Trades
- Maximum suitability for many industries thanks to its high electromagnetic compatibility and good shock and vibration resistance.
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