Abstract: This paper describes in detail based on Schneider Micro and Twido PLC frozen in the beer production line station control system, the system s network topology, process and fault handling, etc..
Key words: Micro PLC Twido PLC Modbus protocol Troubleshooting
1. Introduction
With the rapid development of the automation level, freezing point of beer production line system control and fault handling requirements are also increasing. In this system, use the Schneider Micro and Twido series PLC, and through Modbus bus to achieve coordinated control, remote monitoring, so development of management, which dramatically improved productivity, reduced maintenance costs and maintenance.
2. Products
In this system, each compressor refrigeration unit by Twido PLC to control, through digital modules and analog sensor signal acquisition module, automatic change set out to achieve hand, open stop and fault detection, and to upload first place fault signal monitoring computer.
Twido PLC automation products are a small family of Schneider, a member of the body of 13 units, 15 types of discrete expansion module, 8 analog extension modules can be extended up to 264 I / O, now new TWDLCAE40DRF more integrated Ethernet interface, you can Modbus TCP / IP to equipment connected directly to Ethernet, enables high-speed data communications and remote monitoring easier. In addition, Twido family also added a new member-CAN open module TWDNCO1M, through the module, which enables inverter and intelligent instruments, such as high-speed data communications equipment.
3. System Components and Process
beer production process and the preservation of raw materials finished products, air-conditioning system cooling capacity needed to provide by frozen points. Freezing Point has five open-type refrigeration compressor units, each unit is to Twido PLC to control the core, can be realized automatically according to changes in load conditions and set off on. PLC communication with the system, you can also achieve the coordination of five units. Five units share the same evaporation cooling system. Ammonia liquid cooling system cooling through evaporation, through three sub-panels for ammonia refrigerant propylene glycol unit and system for heat transfer. There were three pump-controlled flow into each plate for the flow of propylene glycol unit, thus ensuring the board for unit outlet temperature can be maintained at -4 degrees Celsius, to process requirements. Units from the board out of -4 degrees Celsius for low-temperature propylene glycol can return to PG (propylene glycol storage tank). Returned from the production site in the PG high temperature propylene tank top, from the board for crew return to the low temperature PG propylene glycol in the lower part of the tank. The temperature of the propylene glycol production process according to the different requirements of high temperature and low temperature by adjusting the mixing ratio propylene glycol, propylene glycol control the temperature of the final reveal the process requirements.
4. control system network structure
control system network structure as shown above. Twido controller Selection compressor series PLC TWDLMDA20DRT, brought its own as a communication port and connected to a text-style man-machine interface. Man-machine interface can be set by the compressor working and operating parameters, manually start and stop compressors, check the compressor run status, view the machine fault situation. Each extension of a PLC communication port, to do Modbus slave, even in the Modbus bus, implementation, and system PLC communication.
systems use Micro PLC Series PLC TSX3721001. Micro series PLC communication is very powerful, supporting Modbus, UN-TELWAY, TCP / IP and other communication protocols. PLC communication system extending a TSXSCP114 card, do Modbus master, through the Modbus network and Twido PLC communications, monitoring five compressor operating conditions. Micro PLC TSX3721 itself with two communication ports, including a communications port and touch screen connected to a communication port and another Ethernet module TSXETZ410 Schneider connected. TSXETZ410 module in this play the role of a bridge, one end through the UNI-TELWAY bus and PLC data exchange system, the other side through the TCP / IP protocol linked to the factory in a small LAN, this LAN monitoring computer can monitor the entire frozen stations operating conditions of the (running on the computer monitor is monitoring software Kingview). Touch-screen user interface of monitor computer back-up equipment, monitor the computer can achieve the same function, the monitor computer or local area network failure, to ensure the whole system can run. LAN on the other system control devices and systems through the LAN PLC to exchange data.
5. Systems PLC of the control functions
Systems PLC communication functions described above in addition to achieve, but also to achieve control of the whole system.
1) of the propylene glycol control of the system. Propylene glycol system processes the following diagram:
use Micro PLC integrated PID function block to realize the automatic control circuit 6, includes three sub-panels for ammonia exit temperature, a 0 degrees Celsius, a -1 degrees C for liquid temperature control a constant pressure for the hydraulic control. Use of PLC s analog data acquisition module, the process of signal acquisition (five temperature signal, a pressure signal), compared with the set value (set value can be set in the user interface), according to the deviation of the results of operations, through simulation output modules, converted into standard signals control the frequency converter and regulator valve opening. Tank liquid level control on PG is propylene glycol system by detecting the pressure of deciding whether to open the valve and whether emptying replenishment.
2) on the evaporative cooling system control. Evaporative cooling system flow diagram is as follows:
evaporative cooling system, evaporative condenser, including three groups, each group including two fans and a circulating pump. Evaporative cooling system with automatic and manual work, manual mode, you can manually start and stop, respectively, and each wind turbine pumps. Automatic mode, according to the size of the condensing pressure, by setting the order to open a certain number of fans and pumps.
3) five compressors coordination. Five compressor can only operate independently, and can automatically put into operation under load conditions and the withdrawal of this case, the compressor input and exit is determined by the system PLC. PLC communications received by the system each compressor working conditions, and then decide Which one under loads into or out of the compressor group.
4) troubleshooting. Through the digital input module or communication, acquisition of all equipment within the system failure state, and under fault grade, to stop the alarm and related equipment and other processing. Through newsletters, upload all the fault conditions monitored computer.
6. summary <BR> The system uses Ethernet host computer and control layer Micro PLC communications, the data collection more efficient and, of course, Twido PLC family added a new member - the built-in Ethernet function TWDLCAE40DRF, therefore, can also use the Twido PLC to improve efficiency, which can significantly reduce costs.