Research Of Hatching Measurement And Control System Based On Fieldbus

With the rapid development of electronic technology, computer and autocontrol, automatized agriculture has been developed gradually, and hatchingcontrol system becomes a heat research point of construciton agriculture. Since90's last decade, because of absorption the experience of foreign production, thesimilar productions of our country have been improved greatly and reachedcertain high level. To meet the requirement of the trend that hatchery growslarger and larger, laneway hatchers gain broad application. While in this kind oflarge equipment, the central conditions controlling, such as temperature,humidity, air-conditioning, egg-turning, etc., influenced result of hatching fatally.So we must design a system on above conditions of security and stability.Meanwhile, the network connection of all hatching equipments is alsorequirement of enlarged hatcheries. Therefore, we put the idea of fieldbus tohatching monitoring system: each hatcher is control by a crunode, and allcrunodes are connected by fieldbus and separately controlled, then connected tocomputers as interface between human and machine.The research purpose of this research is to design hatching control systembased on fieldbus. Fieldbus is a striking point of recent automation development,which is called the local area network of automation. It is the communicationnetwork for the field level devices of process automation and manufactureautomation. It is the integration of field communication system and controlsystem. Adopting fieldbus technology has the advantages as: reducing thequantity and inputs of hardware, reducing installation time and cost, sharing theexpenditure of daily maintenance, increasing the accuracy and reliability, and thecustomers having high active integration privilege of the system, etc. Therefore,based on the economic condition that can be accepted by the farmers in ourcountry, we put the nice idea of FCS into agriculture automation. From theviewpoint of reducing cost, we use all possible advanced technology toagriculture, which is valuable to agriculture equipments on the condition ofChina.Within all kinds of field buses, PROFIBUS becomes the model of openingsystem due to its strict definition, consummate functions and its standard andcurrent technology, which make it one of the most hopeful field buses. ThePROFIBUS-DP is adopted in this system. In this thesis, we systematicallydiscuss the development of the slave interface module of PROFIBUS-DP. Basedon the resource by hand and application requirement, we use MCU, specializedprotocol chip and some other peripheral equipment to fulfill the design of theinterface module. The protocol chip we adopted is SPC3 by Siemens. The SPC3integrates a 1.5Kbyte message frame memory, mode register, status register,interrupt register. The SPC3 handles communications tasks of thePROFIBUS-DP protocol independently. This accelerates protocol handling andreduces the scope of the software in the microprocessor of the interface module.Its maximum transmission rate is 12Mbps, and can automatically detect andadjust its transmission rate. And it is compatible with the microprocessors suchas 80C32, 80X86, 80C166, 80c16 and HC16, HC11, HC916 types. The wholehardware consists of SPC3, AT89S52, bus driver, photocoupler, high-speeddual-port RAM, RTC and Ferroelectric memory, etc. The system communicatesby RS-485 with the bus via SPC3 to receive data, and at the same time exchangedata with hatching controlling nodes by serial port or dual-port RAM, so that toensure the system achieving best control. The balance between cost andperformance of this slave interface module is fully considered from thebeginning of design. The system can easily adjust according to transmission rateon bus, data current of hatching controlling section and different surrounding,while no change is required to applied software, PCB, etc.As to the development of foremost part of the system, the multi-parametercollecting and sensing section is the benchmark of the whole measuring andcontrolling system, and is an important part of the controlling circuit. Accordingto the characteristic of hatching environment and considering the moderntechnologies on sensors, imbedded system, industrial local area network, etc., thedesign of environment control module including intelligent high precisionhumidity and temperature sensing sub-module, micro control unit, real-timeclock sub-module, keyboard display and man-machine interaction sub-module,system monitor sub-module, control execution driven sub-module, field businterface, etc. They have been introduced respectively in this thesis. In the projectthe microcontroller Mega128L by ATMEL Co. is adopted as the core processorof the whole hatching control module. AVR is 8bit RISC microprocessor, whichhas the merits of PIC and 8051 series microprocessor. Its capability of receivingand sending command and data is many times faster than those traditional CISCconfiguration microprocessors. Therefore as main processor, all the outstanding...