modbus serial communication

Two independent asynchronous serial I/O ports are provided for the UART unit of the high-efficiency FIFO serial port based on the implementation of b0x (clock frequency: 60 MHz) on the ARM7, each communication port can work in the interrupt or DMA mode. That is, UART can generate an internal interrupt request or DMA request to transmit data between the CPU and th

Serial communication refers to the use of a data line, one by one, the data is transmitted sequentially, each data occupies a fixed length of time. It requires only a few lines to exchange information between systems, especially for long-distance communication between computers and computers, computers, and peripherals.serial

prototype, the pointer to receive commtimeouts is a parameter: Bool setcommtimeouts (Handle hfile, // handle to communications deviceLpcommtimeouts // pointer to comm time-out Structure); The following procedure sets the serial port read operation timeout to 10 milliseconds: Commtimeouts;Memset ( to, 0, sizeof ());To. readintervaltimeout = 10;Setcommtimeouts (hcom, ); The prototype of the getcommtimeouts () function corresponding to setcommtimeouts

() {$ ("#weight"). Val (res);//Fill the retrieved data to the page} The method of continuous output data of the weighing instrument function Auto_weight () {//if (!continue_auto_weight) {//This is the end of the continuous output flag, as to when the end, depending on the project//return;//}$ ("#weight"). Val (res);send (' 27,112 ');setTimeout ("Auto_weight ()", +);}Summary: About Goole How to connect the weighing instrument, there is time to write the post. finally: If it does not solve the pr

What I want to do is a serial port tool similar to a Super Terminal for AT command applications. The option card interface sends at commands to communicate with the data card, facilitating R D personnel to read and write data cards and testers to test, improve work efficiency.Start with two images:When receiving this task, we must first analyze the two main parts of the software. What are the main technical difficulties? The software includes two par

Serial Communication Flow Control In serial communication processing, we often see the two options, namely, RTS/CTS and Xon/xoff, which are two traffic control options. Currently, traffic control is mainly used in modem data communication, but for general RS-232 programming

First, view the serial device for example, after inserting the USB to serial cable into the switch console port, execute the command:$ll/dev/ttyusb*Second, connecting the serial device $sudo minicom-d/dev/ttyusb0Third, set the serial port parameters in minicom Press Ctrl+a,o, configure

The basic data communication methods can be divided into parallel communication and serial communication:Parallel Communication: it refers to the simultaneous transmission of one piece of data using multiple data transmission lines. It features high transmission speed and is suitable for short-distance

Serial Port is a very common device communication protocol on the computer. --------------------------------- Serial Port Pin definition: 9 Cores Signal Direction from Abbreviations Description 1 Modem CD Carrier Detection 2 Modem Rxd Receive data 3 PC Txd

Tags: this linux path directory port problem view Dev USB1, Linux under the QT serial communication and Windows is the only difference is the name of the port number, Windows is COM, and Linux is the path of ttyUSB02, in general, the Linux plug-in USB to the serial cable can be seen in the/dev/directory similar to the ttyUSB0 like the string of slogans3. Initiali

First, learn some basic concepts. RS232 Level: Logic 1 (MARK) =-3v~-15v, Logic 0 (SPACE) =+3~+15v TTL level: + + is equivalent to logic "1", 0V equivalent to logic "0" TXD: Send data transmit the P31 of single chip microcomputer RXD: Receiving data, P30 of MCU Baud rate: The rate at which a single-chip or computer communicates at the serial port, defined as the number of bits transmitted in binary code per second, unit BTS UART: Universal Asynchronous

Serial Communication Overview There are many kinds of serial communication protocols, such as rs232,rs485,rs422, even the popular USB is serial communication protocol. And the application of