Four Things You Have In Common With Rs485 Cable > 자유게시판

If your application requires RS485, you can use the secondary serial port (serial2) to program and debug your application code using the RS232 protocol, and use the primary serial port (Serial1) for RS485 communications. In the most common multi-drop RS-485 protocol, one computer is designated as a "master" and the rest of the computers or devices on the serial bus are designated as "slaves". RS485 multi-drop networks are daisy-chained networks with a single cable connecting multiple devices. They should generally not be needed, except if you use long cables, multiple RS485 devices, and resistive termination. It provides a convenient means of connecting the QScreen Controller to a variety of peripheral devices, including analog to digital and digital to analog converters, real time clocks, and other computers which use high speed communication. The USE.SERIAL2 command means that the operating system’s terminal interface now communicates via Serial2. The terminal program communicates with the PDQ Board via this serial port. Many terminals and PCs, however, do rely on hardware handshaking to determine when the other party (in this case the PDQ Board) is ready to accept data. Powerful APP Support: SenseCAP Mate APP allows you to set the sensor templates and quickly turn the data logger into the sensor you want.

Because we chose the default baud rate (which the terminal is presumably already set for), you can simply move the serial cable from the Serial Port 1 connector to the Serial Port 2 connector on the Docking Panel to complete the change to the new port. 1 running at the prior established baud rate (typically 115200 baud). If it doesn’t, confirm that the terminal’s baud rate is correct by selecting the Comm item in the Settings menu of the Mosaic Terminal program, and click on 115200 baud. We assume that you are now communicating with the PDQ Board via the default Serial1 port at the standard 115200 baud rate. A jumper labeled "1 485En" (J4) enables RS485 operation on the Serial1 port if the jumper cap is installed, and configures Serial1 for RS232 operation if the jumper cap is not installed. This function properly configures the directions of the SPI I/O pins, and configures the data transfer such that data is valid on the falling trailing edge of the clock, with the clock idling in the low state. An RS485 cable can carry data upto 4000ft (or 1.2km) @ 100kbps as shown below. We can gain insight into the operation of the RS232 protocol by examining the signal connections used for the primary serial port in Table 9 6. The transmit and receive data signals carry the messages being communicated between the QScreen Controller and the PC or terminal.

In this case, cable connections may be made to Serial 2 at pins 4 and 10 of the PDQ Board’s 10-pin Serial Header, or pins 5 and 6 of the Docking Panel’s 10-pin right-angle Serial Header. By default, the RS485 connections are not brought out to the Docking Panel’s DB-9 Serial1 Connector. By default, the RS485 connections are not brought out to the Docking Panel’s DB-9 Serial1 Connector, although custom placement of zero-ohm surface-mount resistors on the Docking Panel can route the RS485 signals to the DB-9. The advantage of using Serial1 for RS485 is that the Serial1 RS485 signals are also available on the Docking Panel, while the Serial2 RS485 signals are available only on the PDQ Board’s Serial Communications Header. In that case, when using very long cables you can improve noise immunity and assure a valid idle level when the transceiver is not active by installing bias resistors. RS485 is however most popularly used in programmable logic controllers and factory floors where there are lots of electrical noise.

Bias termination - Using resistive termination decreases noise immunity, particularly if the cable is loaded with many devices. In these distributed processing networks, a variety of machines and instruments work locally, but communicate and share data or resources with one another globally using a single serial link. Manufacturers are continuously improving the design and materials used in RS485 cables to ensure reliable and efficient data transmission in industrial environments. The end devices are responsible for terminating the cable so that there are no reflections from the cable ends. Two devices are at the ends of the cable, while others are connected somewhere in between. We feature RS232, RS422, RS485, USB, and ethernet devices using copper and fiber. In fact, the program works the same as it did before, but now it is using the secondary serial port instead of the primary port - and you didn’t even have to recompile the code! Using the primary Serial1 port is easy.