B System composition

The core part of the control system is PLC of the S7-300 series from SIEMENS, the followings are included: optional power supply module, CPU module (CPU314), (digital) input module, (digital) output module,

analog module, and three communication modules (CP340)。 After the Communication module #1 being initialized to the communication port RS485/RS232 module, these modules will be connected with five inverters (inverter A- inverter E) with series form in proper order; initializing the communication port of communication module # 1 to RS422 module, and then connecting them with two DC converters in series; communication module #3 is used for the communication between Factory Control Center and the host computer。 The temperature of each the heating zones can be measured and set by the thermostat, thereby the temperature and status of rubber will be controlled; inverters are used to control the host motor, traction motor, accumulator motor, and take-up motor。

C Fuzzy controller design

The Principles of fuzzy control system used in extruder are shown in Fig。2。 Once the Diameter of cable, named Y, is

Fig。 2。  Schematic diagram of fuzzy control

measured by the Diameter Measurement Instrument, it will be compared by the set value, named R, and then both the error ,named e, and its Change rate, named ec will be calculated。 Then these two parameters will be transformed from basic domain to the quantified domain and according to the definition of Membership function for input, both the Membership degree of e and ec can be also be calculated。 Through using E, EC and fuzzy control rules and referring local parameters (Host Load Lp, traction load Lq), the quantified value of output will be tested under the fuzzy synthesis theme。 After de-ambiguous sentences and then get the output fuzzy-based value of fuzzy control, the fuzzy-based value will be changed from the quantified domain to basic domain。 And the control speed forced on host and traction will be received finally。 (p and q)。

III  SYSTEM PROGRAM DESIGN

The software system includes two parts: local control program and monitoring program 。 Local control program are carried on by the programming tools, STEP-5。0 of Siemens。 Local control program can run in a distance far away from the scene of the Factory Production Control Center, which is carried on by the advanced language VB6。0。

A Local control communication program

As mentioned above, Local Communication of this system refers to the serial communication between the two parts: one part contains CPU of PLC, communication module #1 (CP340) ,and communication module #2 (CP340),while   another   part   contains   the  temperature

controller, inverter, DC motor drive。As the communication between the PLC and temperature controller for example, these bellows will describe the design of flow for local control communication program。

BCommunication preconditioning flow

The communication preprocessing flow is shown in Fig。3。

C

Cycle to read and write communication flow

The system requires of all the temperature controller should be read and written at least once per second。 Procedure restarts a certain timer with the interval of 10ms in cycle, reading or writing will be completed by once during the interval time。 After communication cycles have been repeated for 32 times, the register MW100, MW104 will be reset separately to 100,200。During the former time of 16 cycles, the set value (s1) will be written to temperature controller, while in that another half time the actual value (M1) will be read from temperature controller。 The actual value of temperature is by ASC Ċ code ,which will be transformed into integer 。And then the results will be displayed on the proper screen of the controller according to the live console, or written into the register of PLC according to the touch panel of temperature controller’s actual value display。 The other logic control procedures will also be executed before the next period of timer。 The flow chart is shown in Fig。4。