The Design And Implementation Of Data Acquisition System Based On The OPC Transmission

Based on DCS， a set of processs-control systems can be built in a certain largehelium low-temperature system， mainly conducting systematica control and datacollection in the process of large magnets’ temperature falling. As for the commondata， the low-temperature system can receive standard signals of4~20mA by itsown parts. But some complicated data in the system cannot enter the DCS systemdirectly and so some measures must be taken to deal with the data such as somesignals of deep low temperature， rate of flow， vacuum and liquid place.To solve such problems， there are two methods for both domestic and foreignDCS systems. One is to change the signals by extraordinary meters， but theconverting modules are too expensive， most of which are foreign products. Theaccuracy of domestic products can hardly meet the needs， so the foreign productshave to be bought and as a result， the cost will increase. The other method is tocompose the third party program and to transfer it to the DCS system based on theOPC data.Made by the OPC foundation， OPC(OLE for Process Control) technology is anorm for mutual operations of industrial controlling software， which is also atechnology carried out by Microsoft together with the controlling field to applyWindows to the controlling systems. Its function is to build an interface standardbetween industrial controlling systems and application programs and to build aunified norm for storing and collecting data between industrial controlling deviceand controlling software.The main task of this project is to build a set of complicated data collectingsystems， based on the study of the data transferring technique of OPC. This set ofsystems can collect and deal with some complicated data timely and then transfer thedata to the DCS system. Besides， it can receive the data from DCS and do thecorresponding calculations.The whole DCS system has already been built by American Emerson’s Delta Vsoftware. The Delta V software has the OPC server integrated， and so only the OPCcustomer terminal program needs composing. The hardwares involved in thetemperature collecting program are mainly collecting cards，amplifiers，ConstantCurrent Source，Keithley. Other devices are sensors such as vacuum meters andbuoyancy liquid meters.On one hand， the building of such a set of systems solves the problem ofcollecting data in low temperature systems and reduces the cost. On the otherhand， it can deal with the data collected and the data of the DCS system mutually，call the third party program and improve the system. The study of this project is ofgreat importance to the data collection under low temperature and to accumulateexperience in measuring data under extreme conditions，communication，diagnosisand some other aspects.