Filling is composed of management, control layer and field layer, the management is an industrial computer (upper computer), as a man-machine interface, the industrial computer through the Kingview software and control layer exchange data, composed of fieldbus control board, directly inserted in the slot of the industrial computer motherboard, can realize the equipment layer for data acquisition, program control and information exchange with the management. WORX software conforming to IEC1131-3 standard is adopted, including configuration software SYSTEM WORX and programming software PROGAM WORX. The control program adopts hierarchical structure and modular programming idea. The lower module is called by the upper module. By designing the basic function module of each layer, the control, serial communication and online diagnosis functions are realized at the top level. The following describes the communication module, main control function module, and online diagnosis module.

The liquid Filling machine is programmed in the structured text language provided by WORX and is responsible for sending information to the peripheral display. The communication module mainly calls the peripheral device communication function block provided by WORX. Because the information sent to the peripheral device is relatively long, the string to be displayed plus the identifier at the beginning is 50 bytes in total. In order to prevent the following data from overwriting the previous data and ensure the reliability of the sent data, the STRING_TO_BUF function block provided by WORX is called. First, the identifier and the string to be displayed are written into a data buffer, combined into a 50-byte string, and then the P_WRITE function block is called to send the information to the peripheral device.

Filling control signal input/output interface is used to connect the external signal input and control signal output, sending signals from the PLC, respectively, for tare, tare reset and data retention; Remove the tare before each weighing, then the net weight is immediately set to zero, the data is maintained after the final weighing value, and the tare is reset after the end of the feeding, that is, the peeling operation is canceled. At this time, the gross weight and net weight are the same value, which can ensure the net weight of each weighing. There are 5 signals sent to the PLC, which are close to zero, preset value, drop value, insufficient, excess, and upper limit. In the PLC program, the drop value of this signal is sometimes used as a final value signal, the weight to the drop value when the control door is closed to end the feeding, the time only exists when the valve is closed, the size of this value is the weight that has not fallen into the weighing bucket after closing the control door.