Automatic Dosing Machine Control Scheme Based on Soft PLC and CAN Bus Published On :2017-05-21Views :
CAN (Controller Area Network) that is the controller LAN, mainly used for a variety of equipment monitoring and control of a field bus. It has a simple structure, flexible communication, long communication distance, the use of non-destructive bus arbitration technology and so on. CAN bus for the industrial control system in the high reliability of data transmission provides a new solution, it has been widely used in foreign industrial measurement and control field, so the program uses CAN bus interface, the use of ADLINK developed double mouth Isolation non-intelligent CAN adapter card PCI-7841, the card supports CANopen, DeviceNet and other CAN bus application layer protocol; and provide VB, VC programming function. Through the man-machine interface, the operator's control instructions to the intelligent weighing display control part, at the same time, accept the intelligent weighing display control part of the signal and data to be analyzed and processed and displayed.IPC display interface shown in Figure 2.
Figure 2 IPC display interface
3.2 intelligent weighing display control part
At present, the market does not have CAN communication interface of the packaging machine dedicated controller, so intelligent weighing display control part of the need for independent development. In order to shorten the development cycle, through the existing controller for technical improvements, increase the CAN communication part. This part of the Intel microprocessor 89C51 as the core, through the sensor, A / D conversion acquisition weighing signal, after processing, according to the need for this information through the SJA1000 and CAN interface circuit (mainly composed of PCA82C250) sent to the CAN bus On, with the upper industrial computer to communicate. The SJA1000 is an independent CAN controller manufactured by PHILIP, which conforms to the CAN2.0B protocol and has all the necessary performance required to complete the high performance communication protocol. It can complete all the functions of the physical layer and data link layer of the CAN bus protocol. PCA82C250 is the interface between the CAN controller and the physical bus, which can improve the differential transmission capability to the bus and the differential receiving capability of the CAN controller and improve the anti-jamming capability of the bus. The part of the functional diagram shown in Figure 3.
Figure 3 intelligent weighing display control part of the functional block diagram
4 concluding remarks
The control system uses CoDeSys and CAN bus technology to simplify the hardware structure, fully meet the requirements of open architecture, to meet the industrial automation field of control system openness and flexibility requirements for future industrial automation to a higher level of integration Reliable technical support. After the simulation test, the control program to achieve the desired results, has a very broad application prospects, and can produce good social and economic benefits.
