Design of well group control system based on wirel

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Design of well group control system based on wireless communication network

1 preface

at present, there is no better control scheme in the control of water supply wells of railway locomotives in China. Most of them use manual pump startup and pump shutdown. Staff patrol to check the operation of each well. On the one hand, due to the lack of necessary protection measures to bear various external loads, overvoltage, overcurrent and phase loss, it is easy to burn the motor; On the other hand, due to the long distance between wells (several kilometers away), the inspection time is long, so it is difficult to master the operation of each well and the work efficiency is low. In recent years, railway technicians have made many attempts to change this backward control mode and improve the working conditions of workers. This paper introduces a distributed well cluster control scheme composed of industrial control PC, STD and interphone

2 hardware design

2.1 overall design scheme

because the measurement and control points are scattered, the system adopts distributed control mode. The main control room adopts industrial PC as the host, which is mainly used to complete data processing and display, output data reports, transmit data transmission commands to each terminal machine circularly, receive the data sent by the terminal machine, and send motor start and stop commands to the terminal machine through man-machine dialogue function; The terminal adopts STD industrial control computer, which is mainly used for data acquisition, motor control, overvoltage, overcurrent protection, etc. The communication between the host computer and the terminal computer adopts wireless mode. In the figure, the terminal adopts the black box working mode (without display and keyboard), the CPU board adopts std5081, which adopts 8088 CPU, and the clock frequency is 5MHz. The std5442 A/D sampling board is used to sample the voltage, current and pressure at the end of production, with an accuracy of 4 ‰. STD 5388 pulse input board is used to measure water flow and power consumption. STD 5337 reed relay output board is used for motor start and stop control and motor state detection, and 8 reed relays (ds2y-s) are installed on the board. Ds2y-s is a double pole double throw electronic switch. There are two groups of switches, one for controlling external circuits and the other for system inquiry. STD 5799 bus signal matching board is adopted to reduce the interference of power spikes and instantaneous disturbances and other noises on the bus motherboard

2.2 wireless communication line

the system adopts wireless communication mode for data transmission. The wireless modem adopts STD 5641 modem (terminal machine, host machine adopts ipc5641 modem) remote data communication board, which adopts FSK modulation mode to modulate serial pulse signal into audio signal, and communicates through interphone. Figure 2-2 gives its principle block diagram. The modulation and demodulation chip used on the board is a large-scale analog and digital hybrid integrated circuit am7910. In the figure, "FSK in" is connected to the interphone microphone (MIC) or the input point of the audio amplifier behind the microphone; "FSK out" is connected to the audio output point of the interphone

3 software design

3.1 communication protocol

the system adopts the master-slave working mode, and the host sends control commands or data transmission commands to each end machine at fixed time, and each end machine completes corresponding actions or transmits data to the host machine according to the commands

(1) control command communication protocol

the format of the control command transmitted by the host to the terminal is as follows: num: terminal number, accounting for two bytes, ranging from 00 to 15.

com: control command, a byte, defined as follows:

start/stop motor command:

o - start motor; C - turn off the motor.

data transmission command:

U - three phase voltage; I - three phase current;

p - pressure; L - flow;

D - power consumption; S - current motor state.

(2) the terminal machine transmits the execution information structure to the host machine

the terminal machine receives the control command, executes the operation of starting and stopping the motor, and transmits the execution information to the host machine. The format is as follows: num and com definitions are the same as the previous.

msg: execution information, accounting for one byte. The values are as follows:

s - the command is successfully executed;

q - the electric voltage is too low to start, for example, suppose the expanded configuration of the sensor is in a 10 torque telephone;

u - the electric voltage is too high to start the motor;

o - the motor cannot be started due to other conditions;

w - unable to stop the motor.

(3) the data information structure transmitted from the terminal to the host computer is the upward transmission

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