Application of the hottest twidoplc in central air

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Application of twidoplc in central air conditioning

simple and safe operation 1 With the faster and faster urbanization process in China and the continuous improvement of people's living standards, the demand for central air conditioning is increasing, and it has become a necessary equipment for cooling and heating of large-area buildings. At present, central air conditioners mainly include fuel oil and gas medium-sized central air conditioners, ground temperature central air conditioners, fully enclosed screw chillers, semi enclosed screw chillers, air-cooled and hot-water units and other products. Schneider Electric automation products have been successfully applied in fully enclosed water chillers and semi enclosed air-cooled units

2. Product introduction and =s= product scheme

relatively speaking, the technical content of the fully enclosed screw chiller is higher, so the control system is complex, while the air-cooled chiller is simpler

therefore, the first fully enclosed screw chiller is composed of =s= company's Micro PLC and xbtf. Its main composition is:

tsx3721 + tsxdmz25dr + tsxdsz08r5 + tsxaez801 (PCS)

in this control system, the control principle and process are not very complex, but the machine has high requirements for fault alarm and protection, so you can see very complex protection logic in the program; In addition, the machine has a special place, that is, there is a data table composed of thousands of discrete data. The operation state of the machine is based on the data table. In a sense, the high operation efficiency of the central air conditioner depends on the accuracy of the table. In this way, the data table becomes the know-how of China's air conditioning enterprises. When using micro PLC, the customer made good use of the function of converting constants and internal words in micro PLC, stored these data in the constant table, and used the table lookup function to get accurate data

the air-cooled unit is relatively simple in technology, and its market price is lower than that of the fully enclosed unit, which has cost requirements for its parts. Therefore, in the design, it adopts the Twido PLC, which can not actually produce and sell the relatively higher cost performance after it is put into production, and the new touch screen xbtg launched by Schneider Electric. The basic composition is: twdlmda20drt+twdddi8dt+twddra8 (16) rt+


2005, With the entry of a large number of domestic enterprises, the price of central air-conditioning enterprises has decreased significantly, and the cost pressure of the industry has suddenly increased. Therefore, the customer requires a low-cost alternative to the relatively high cost micro PLC control scheme, so as to reduce the cost; Based on this starting point and considering the successful application of Twido PLC in its semi enclosed air-cooled unit, the customer recognized Twido PLC, which is very close to micro in quality and performance. Therefore, we gave a scheme that Twido replaces micro with high transparency, excellent mechanical properties, high thermal deformation temperature and natural halogen-free flame retardant characteristics, and gave priority to the multi-channel analog module newly launched by Twido in this scheme, Thus, the cost of the system is greatly reduced compared with the original. The new configuration is:

twdlmda20drt + twdddi8dt + twddra8 (16) rt + twdami4ht()

in this application, we have encountered a technical difficulty: how to complete the table lookup function of thousands of variables in Twido PLC? At present, the maximum number of memory words in Twido is 3000, so thousands of data will occupy a lot of memory resources. In order to solve this problem, we have made good use of the programming skills of subroutines, which have been adjusted when leaving the factory. Thousands of data are divided into dozens of subroutines by using the assignment program, and the same data area is used in the subroutine, which solves this problem very well. Moreover, since the data of each subroutine is less than 100, its query speed is faster than before

in this system, we still choose Schneider Electric's new touch screen XTBG to cooperate with Twido. In the programming process of xbtg, I found that the megelis xbtg series products have a large memory and have a powerful function of writing Java scripts. We can skillfully put a huge data table into xbtg for query, that is, define the same number of variables as Twido PLC's table lookup function in xbtg, and set the initial value of the variables as table values, Write a script to find the value of the address given by Twido and send it down to Twido. In this way, the technical obstacles are bypassed and the powerful data processing ability of xbtg is shown to customers

3. Conclusion

this system uses Schneider's complete solution, which mainly has the following characteristics:

a) make full use of the large amount of memory space inside the xbtg touch screen to store user process parameters, simplify the programming work of Twido PLC, and make the PLC system easier to maintain

b) adopt the newly released highly integrated analog module, which greatly reduces the system cost

c) use a full set of Schneider products, such as xbtg man-machine interface and Twido PLC, so that the control system can better integrate with each other and realize seamless communication

d) use the advanced language programming function of xbtg touch screen to preprocess the process parameters, improve the calculation accuracy and speed, and further improve the performance of the whole control system

so far, the customer has used Twido PLC for nearly three years, and hundreds of machines have been delivered, which can operate successfully all over the country. The new scheme effectively reduces the product cost and improves the product competitiveness on the premise of ensuring the product quality

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