The ship main engine remote control system based on programmable controller design

1 the introduction in the field of ship automation is an important part of the main engine remote control system. There are many types of main engine remote control system technical scheme based on the PLC industrial control network to realize the function of main engine remote control system, has the good economic performance, the characteristics of the hardware circuit structure is simple, safe and reliable work. In PLC controller control network to realize the main engine remote control system design, on the basis of discussion the general structure of the main design the PLC network and communications solutions, and through the communication network of the host start stop part of the design of automatic control and security system. 2 main engine remote control PLC network control overall structure design and the realization of the communication methods 2. 1 main engine remote control PLC network control overall structure design of PLC control network to control the main engine remote control system, including two S7 - 200PLC controller。 One of them to control the host start stop and speed adjusting, installed in the mechanical control room; Another is used to complete the task of electronic governor, installed in the engine room. Setting up a computer as a monitoring platform for monitoring the important signal of the whole system. The main equipment for the entire network: two S7 - 200 PLC, a micro computer, network connectors, and RS - PC/PPI cable 485 cable. According to the overall communication design ideas, our overall structure design as shown in figure 1. Figure 1 overall structure diagram as shown in figure, the main PLC communication mouth out the earth bus connector through the network and PC/PPI cable and respectively from the stand of PLC and computer communication. Through the RS - between master-slave station 485 bus for PPI protocol communication, master station and computer terminals through the PC/PPI cable free port communication. Come out from the main PLC communication port connected to the network connector, is for the sake of isolation, lest RS - computer 232 damage. Through the network connector out ground - and RS 485 A and B signal by comparing high and low level and from the station to communicate. At the same time, through the PC/PPI cable connectors which leads to the needle through the RS - 5 And RS - 485 232 into 3 line receive, send and ground, respectively, to communicate with the computer. S7- 200 pinout of PLC communication mouth see table. The communication port pin assignment 2 schedule. 2 a combination of communication protocol and debugging in S7 - 200 network communication, can realize two kinds of communication protocol to communicate and not interfere with each other. But the premise is two kinds of agreements of the baud rate must be the same, since there is only one communication port, baud rate only support 9600 baud, therefore in multi-protocol communications, baud rate is set to 9600 baud. For multi-protocol combinations, time-sharing multiplexing method, the author adopted the bus at the bus control, the author through several timer of rectangular wave, thus forming height respectively in the different periods of PPI protocol communication and free port communication. The main program flow chart shown in figure 2. PPI communication processes as shown in figure 3. Free port communication program of the process as shown in figure 4. Figure 2, the main program flow chart shown in figure 3 PPI communication program flow chart of 4 free port communication process carried out in accordance with the above scheme of system design is completed, the actual communication effect to meet the design requirements, from the stand of PLC and computer terminal can largely from the main information within 20 ms. 3 3 main engine remote control system design. 1 start stop part of the design, the author selected objects in the process of design is one of the most common B&M low-speed machine, start-stop control mainly includes five parts: starting control, slow turning control, parking control, repeat starting control. Ahead starting, for example, the system must be in two situations: starting and normal starting, reverse parking situation can ensure car starter solenoid valve on and off, and shall determine the starting state, ahead of starting processes as shown in figure 5. Figure 5 is the car starting processes slow turning control is to consider stopping time more than 30 min and power restored after a power outage two cases. On the host around a circle or an emergency control signal, can cancel the slow turning control. Is to consider parking control is divided into four kinds: parking instructions, the fault signal, cars that do not agree with running direction and starter solenoid valve during the work. Repeat starting a control program is divided into four subsystems: starting time monitoring subroutine, reversing time monitoring subroutine, count starting intermittent delay subroutine and repetitive starting number subroutine. Program flow chart above due to the limitation of space, in this not a tautology. 3. 2 speed control part of the design of this design is to read with analog input module EM235 telegraph instructions and speed feedback. PLC host first read in analog, through three shift, can get 12 digital signal, and then through the timing interruption program to the input digital filter, filter after the data with the normal signal voltage range is determined by external circuit, which can diagnose the three terminal of car makes potentiometer without break line fault, after the signal to ensure smooth, then treated with various restrictions, restrictions on link includes critical speed limit, acceleration constraints and load the program limit, limit after processing the results of the last from standing by PPI communication protocol to send electronic governor of PLC to control the speed of the host. Rev limit processing program flow chart shown in 6. Figure 6 speed limit handler process another task of this design is reading speed feedback value and carries on the processing, the processed to get various running status of the host, including the host and reversing of the reversing speed and combustion speed and accelerate the breaking point, on the one hand, needed to get the start-stop control host state information, on the other hand make monitoring platform can be real-time monitoring, intuitively reflect the current state of the host, at the same time can show the whole process of speed change.
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