1.3 How to use the streaming formula

The use of streaming sockets is based on a connection protocol. Before connecting and receiving data, a connection must be established before data can be read from the data stream.

First, the server needs to create a set of blocks for listening. After assigning an address to the set of words, the listen() function is called to make it in the listening state; after the client creates the set of words, it allocates the set of words. The address, then call the connect() function, requesting a connection to the server socket; the server socket word, after receiving the client's connection request, calls the accept() function, which creates a socket for the connection. By applying the set of words and the connection set words on the client, data can be transferred between the server and the client. After the end of the transfer, both parties call the closesocket() function to close the socket. The method of use is shown in Figure 3.

Figure 3 Streaming block communication process

2. Implementation of network control system

2.1 Network Control System Principle

The network control system software runs on the client and the client connects to the server via the LAN. The CNC system of the machine tool runs in the server. First, the local CNC system of the server is started. After the initial setting, the network control state is entered, the listening suite is opened, the connection request of the client is waited, and the connection request of the client is received. After that, the online information is verified. If the online condition is met, a connection is established with the client, and both parties can send and receive information or instructions to each other. The CNC system of the server can use the CCD to collect the machine processing status image and parameters in real time under the network control state, save the image in bitmap format and send it to the client to display the processing status, and send the status parameter to the client in real time. The CNC machining code can be edited in the client's remote control system software, then the NC code is passed to the server and downloaded to the PMAC for control commands. The machine tool processing control command is sent from the client to the server to control the machine tool operation, and at the same time, the information sent by the server is received, and the machining condition of the machine tool is dynamically monitored. Through the remote control program, the client can also modify the machine's machining parameters online and debug the machine.

2.2 network control system hardware structure

The network control system of CNC machine tool adopts modular hardware structure. The numerical control system adopts "PC+NC" structure, the PC adopts Pentium 4 host, the NC part adopts open multi-axis motion controller PMAC2-PCI; the network system adopts "server + "Client" mode, the CNC system runs on the server, the network control software runs on the client, the server and client are connected to the Intranet/Internet through the network card and communication cable, and the CCD camera is installed on the CNC machine to monitor the machining status of the machine. And through the image acquisition card, the operation of the machine tool can be collected and saved in real time. The hardware structure of the system is shown in Figure 4.

Figure 4 network control system hardware structure

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