S7-300 PROFIBUS DP system configuration PLC Programming

PROFIBUS DP master system configuration with DP systems can be divided into port, using the communication modules CP master system and the DP system with intelligence from the station. DP master system three kinds of systems with DP port, using the communication modules CP master system in the hardware configuration is basically the same.
 
One 1. PROFIBUS DP system: mouth with DP master / slave system
DP port with master / slave system design is very flexible, which allows the CPU to store different data areas DP process data. The data area depends on the type and application CPU. Process image, bit memory and data blocks can be used for DP input and output data.
Process image data distribution standard. In the process image of the CPU must have sufficient space to maintain a continuous DP input area and a continuous output area. This may be limited by the central configuration process image signals and the number of modules.
Bit memory and the same process image, this area is suitable for global storage of DP signals. For example, if the process image available space (not the central signal modules occupy space) are not enough, you can use the bit memory area.Blocks can also be used to store the data signals DP. The best use of this time is stored in the relevant DP data area only to be called a program.
F build hardware configuration S7-300 PLC master station (with DP port): Double-click the “X2 / DP” column or “CP342-5” column in the dialog box, select the “DP-Master”
F add ET-200 PROFIBUS slaves on the bus:
Master / can not be repeated from the I / O address of the station, which is assigned by the system software. If you need to edit the address, you can reset the dialog template properties.
2. PROFIBUS DP System II: with communication modules CP of the master system.
Using communication modules CP master / slave system, the master / can be repeated from the I / O address of the station, because the system is equivalent to two of the PLC CPU. You can use the Properties dialog box template arbitrarily set I / O address, or just can not be duplicated from the master I / O address inside the station.
When configuring the CP, you must set the operating mode. (Operating Mode)
CP342-5 DP always need to DP-SEND and DP-RECV. These chunks through the backplane bus for transferring data between the CPU and CP.
CP342-5 data is always transmitted continuously. The maximum length of the master data is 240 bytes and the maximum length of the data from the station is 86 bytes.
DP-SEND (send) the data in the CPU specified DP data area to the PROFIBUS CP sends a transmission buffer for transmission to the DP slave; DP-RECV (receive) data is read from the DP slave, the PROFIBUSCP receive buffer data into the CPU specified DP data area.
DP-SEND (transmission block) and DP-RECV (receive block) structure
 
Types and Functions DP-RECV (receive block) each terminal parameters
 
Types and function DP-SEND (transmission block) each terminal parameters
 
3. PROFIBUS DP system of three: with intelligent systems from the DP station.
The main features are intelligent slave: DP master the required input / output data is not directly from the real input and output ports, but from the preprocessing CPU.