The Siemens S7-200 PLC supports multiple communication modes such as Point-to-Point Interface (PPI), Multi-Point Interface (MPI), and Profinet DP. PPI protocol is commonly used for communication between Siemens devices and for programming the PLC. In Free Port mode, users have full control over the serial interface to implement custom communication protocols. This allows greater flexibility in system design. Using ladder logic, users can call receive and send interrupts, as well as use commands like XMT (Transmit) and RCV (Receive) to manage communication tasks. In Free Port mode, the entire communication protocol is handled by the user’s program. The communication port on the S7-200 CPU uses a 9-pin D-type connector compatible with RS-485. A PC/PPI cable is also available, which connects RS-485 to the RS-232C port of a computer, making it easy to set up hardware communication between the S7-200 series PLC and a PC. The programming software for the S7-200 is STEP7-Micro/WIN32, which offers three programming languages: STL (Statement List), FBD (Function Block Diagram), and Ladder Logic. It includes two types of instructions: SIMATIC instructions and IEC 131-3 standards. The example provided here uses STL with SIMATIC instructions. When implementing a communication program on the S7-200 PLC, the program is typically divided into a main routine and interrupt routines. The main program initializes the communication port, enables interrupts, and handles data transmission and reception. The interrupt routines are responsible for receiving and sending data. The RCV command is used to start or stop the receive operation, and it requires defining both the start and end conditions. The XMT command sends data through the communication port in Free Port mode. The selection of the control word reflects the status of the CPU's mode switch, which is monitored via SM0.7. When SM0.7 is 0, the mode switch is in the "TERM" position; when it's 1, the switch is in the "RUN" position. Free Port communication is only possible when the switch is in the RUN position. SMB30 is the Free Port mode control byte that sets parameters such as the communication protocol, baud rate, and parity. Detailed settings for other control words can be found in technical manuals. Here’s a brief overview of the program: NETWORK1 LD SM0.1 // First scan MOVB 16#09, SMB30 // Set Free Port mode: 9600 bps, no parity, 8 data bits MOVB 16#7C, SMB87 // Receive message status byte MOVB 16#53, SMB88 // Set the start character "S" MOVB 16#45, SMB89 // Set the end character "E" MOVW +5, SMW90 // Set idle line interval (ms) MOVW +179, SMW92 // Intercharacter/information timer timeout (ms) MOVB 60, SMB94 // Number of characters to receive NETWORK2 LD SM0.1 MOVB 16#53, VB2499 // Set the starting address of the receive/send buffer ATCH sent_interrupt, 9 // Link send completion interrupt with subroutine ATCH receive_interrupt, 23 // Link receive completion interrupt with subroutine ENI // Enable interrupts
Chinese Tier 1 brand Solar Panel (Longi, Jinko, Trina, Canadian, Ja etc.)
This type of product is mainly Tier 1 solar module product in China, include Longi solar panel. Jinko solar panel, Canadian Solar panel, ja solar panel etc.all of which are among the top 10 world-renowned brands. The original A grade product is mainly mono crystalline and half cut cell solar modules, with a power range of 400watts to a maximum of 700watts.quality warranty is 25 years.
A grade, this type of film is characterized by a neat and uniform appearance, printed electrode grid lines, no broken grid, no surface stains, no leakage, no aluminum package, no hidden cracks, no scratches, no black core, no reverse current, stable electrical performance, and high conversion efficiency
Using solar cell testing equipment to measure and screen, the conversion efficiency, filling factor, and appearance that meet certain standards are first level. Generally, the conversion efficiency, filling factor, and appearance of first level are better than those of level B
The level of solar panels can be divided into first level, second level, third level, and fourth level, and the first level components can be divided into first level+and first level - two levels. The second level is also the same, and the cost difference between different levels of solar panels is also very large.
Chinese tier 1 brand solar panel
TIER 1 brand include
Longi, Jinko, Trina, JA, Canadian, znshine, etc.
quality warranty
25 years
grade
original A grade (each solar panel can be checked on official website with barcode)
power range
400watt to max 700watt
Tier 1 Solar Panel,Mono Solar Panel N Type,Solar Panels Bifacial 555 Watt,Solar Panel Mono Topcon Cell
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