1 Proverbs In order to meet the needs of modern social, economic and military development, it is necessary to develop unmanned emergency and standby power stations. Microcomputer-monitored automated diesel generators are a good choice. The system developed by the author basically satisfies the functions of automatic detection, automatic display, automatic start, shutdown and telemetry, remote display and remote control required for automatic monitoring. Due to the harsh working environment of the system, in the development process, in order to ensure the stability of the system (especially the lower computer), a series of measures have been taken to enhance the anti-jamming performance of the system.
2 lower machine system bookmark2 is to enhance the anti-interference performance and reliability of the system. The following measures are taken in hardware: through appropriate parameter selection, the noise in the input signal can be effectively suppressed. 2 High speed is adopted in the signal input channel and the control output channel. The optocoupler is isolated.
The woman is owed by S to the taxi! It is said that the method is separated from the analog ground and the digital ground by Xie T today to avoid the interference of the analog circuit to the digital circuit.
4 monitor chip for voltage monitoring and watchdog protection. When the system voltage is less than 3.6V, use the 8051 external interrupt INTO alarm, the RAM should be charged with battery protection, when the system is powered down, it can automatically switch to the backup power supply to protect the important data in the RAM. The watchdog prevents the program from entering an infinite loop.
5 Use a large area of ​​ground on the board to effectively suppress ground interference. Coupling capacitors on the power and ground of important chips.
6 In order to prevent the system from malfunctioning during reset or interference, the graduate student C research MonfC ublishi uses two relays in the control circuit to perform the self-locking protection circuit principle as shown in Fig. 2. 1 and 2 are switches controlled by a microcomputer, and switches K1 and K2 are normally open and normally closed. Control 1 is closed and relay K1 is energized and self-locking. To de-energize relay K1, first turn on 2, let relay K2 get power, make switch K2 open, and then control 1 open. Therefore, relay K1 can only be activated when K2 is energized and K1 is de-energized. Greatly improve the reliability of the system.
―2 Control Circuit Schematic Figure 7 uses a dedicated microcomputer power supply to avoid power supply interference.
3 lower machine program statements to prevent incorrect execution of statements.
Software trap technology is used to prevent programs from entering the dead zone.
The key code is used in the button program. When the button performs the control function, the password must be checked before it can be executed to prevent misoperation.
Set the program control flag before executing each control function subroutine (normal start, emergency start, normal shutdown, emergency shutdown, or normal operation). If the system is abnormally reset during the execution of the program, the system can automatically recover to the previously interrupted subroutine to ensure the continuity and reliability of the system.
4 Communication between the upper and lower machines The upper computer communicates with the lower computer through RS232 (short distance) or MODEM (long distance) with VB programming. The control interface can simulate and digitally display the controlled parameters; it can display the mains status and the running status of the unit; it can display the cause of the unit failure; it can control the normal start, emergency start, normal stop and emergency stop of the unit.
The host computer uses the MSCOMM communication control to communicate with the lower computer. 8-bit data, 1 stop bit, no parity, wave 9600. The lower computer actively calls, and the upper computer applies the clock control TIMER to handshake and start communication by waiting, querying, and answering. The communication protocol is as follows: C host computer sends and transmits data request: 1EH D lower computer transmits data format: F host computer sends transmission control command request: 4BH. G lower computer agrees to transmit control command Answer: 4CH. H control command format: emergency start :11H; normal start: 12H; emergency stop: 13H; normal stop: 14H. I lower position machine or get an answer error, send OGH. Display parameters (frequency, voltage, current, power, oil pressure, oil temperature, water temperature , speed) are 4-bit ASC code data. The check code is 35 bits. The soft addition is added to the friend sentence before the addition of verbose %lish data and H such as | can be timely: (down to the eighth sentence by the formula (3-1), the partial pressure The resistance R has a great influence on the Ui, and the resistance change can be completely transmitted. The method for improving the temperature stability is to use a high-precision metal film resistor having a temperature coefficient of 0.1% C or even 30 ppm/C instead of a temperature coefficient of 0. resistance.
―2 detection schematic diagram-2 shows that the DC voltage U obtained after the AC signal Ui is detected is the required voltage signal proportional to the displacement, U is proportional to the peak-to-peak Upp of Ui, but at the same time, the detection function is completed. The diode is related to the tube drop Ud.
―2) The signal U depends not only on the displacement but also on the forward voltage drop of the diode. The forward voltage drop of the diode is very sensitive to changes in ambient temperature, which is another important cause of zero drift of the preamplifier.
Through comparison experiments, it is found that the output voltage of the detection circuit using silicon diode and germanium diode respectively changes with the change of temperature. It is observed from the temperature rise of 25 ~ 45C at room temperature that the output voltage U of the silicon diode circuit is increased after the detection, and the output voltage U of the manifold circuit is lowered. If the detector circuit is matched with different silicon tubes and manifolds, the output voltage will be effectively suppressed with temperature changes.
Under the same temperature rise condition of 25~45C, the output voltage of the detector circuit using the same kind of silicon diode changes more than 0.1V, the output voltage of the neon tube changes to 1V, and the output voltage of the hybrid diode circuit changes by 0.03V. After suppressing the zero temperature drift, the temperature stability of the sensor is significantly improved. As shown in 3, when the room temperature is changed from 22 C to 32 C, that is, the temperature difference is 10 C, the maximum drift of the output voltage of the improved sensor is 0.4 V, which is equivalent to 0.07. 4 Conclusion Based on the virtual instrument technology, a low-cost centrifugal unit rotor vibration monitoring system is developed. The system operation results show that compared with the traditional test system, the virtual instrument solution not only has a compact system structure, flexible structure, low cost, and can realize remote monitoring, and the function is easy to expand by modifying the software. Therefore, the application prospect in rotor vibration monitoring is very broad.
8-channel eddy current displacement sensor. In view of the key factors affecting the temperature stability of the sensor, measures such as improved circuit design and optimized components are adopted to reduce the zero drift to the original V10 and meet the test accuracy requirements.
Cheng Hu. The status quo and development trend of virtual instruments. Modern science instrument. Instrument technology Yuan Xiguang. Sensor Technical Manual. Beijing: National Defense Industry Press. north. Journal of Instrumentation. 1994,. The Journal of Tsinghua University, 1999, (continued from page 53) or correctly received the response of the host computer, will terminate the communication program; the data transmitted by the following machine will be re-transmitted into Dumu Ma Technology. The principle and application of single chip microcomputer. Beijing Hope Electronics. Mechanical Industry Press.
Wang Shuiliang. The microcomputer controls the anti-interference measures of the process channel. Electrical measurement and instrument
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