识别传送和接收（国外英文资料）.docVIP

识别传送和接收（国外英文资料） Use the free port mode to control the serial port Return to the top You can choose the free port mode to control the s7-200 serial port via the user program. When you select the free port mode, the program controls the communication port operation by using the receive interrupt, the transport interrupt, the transfer instruction, and the receive command. The communication protocol is completely controlled by the trapezoidal program when it is in the free port mode. SMB30 (for port 0) and SMB130 (for port 1, if the s7-200 has two ports) to choose the baud rate and check. When the s7-200 is in the STOP mode, the free port mode is disabled and normal communication is rebuilt (for example, programming device access). The simplest case, you can only use transfer (XMT) send a message to the printer or display. Other examples are connected with a bar code reader, weightometer and welder. In each case, you have to write the program, supported by S7-200 is located in the free port mode with the communication of the protocol used equipment. Free port communication can only be used when the s7-200 is in the RUN (RUN) mode. Set an 01 value in the protocol selection field for SMB30 (port 0) or SMB130 (port 1), enabling the free port mode. In the free port mode, it is not possible to communicate with the programming device. Tip: use the special memory bit SM0.7 control to enter the free port mode, which reflects the current location of the action mode switch. When SM0.7 equals zero, the switch is in the TERM (terminated) position; When SM0.7 = 1, the operation mode switch is located in the RUN (RUN), you can use the programming device by using the method of change will switch to any other location monitoring or control of S7-200. Change PPI communication to a free port mode Return to the top SMB30 and SMB130 configure the communication port 0 and 1, as a free port operation, and provide the baud rate, check, and data bit selection. SMB30 and SMB130 describes the fr