• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

The primary and secondary serial communications ports are accessible through the PDQ Board's 10 pin, dual row Communications Header (H2) and through the Docking Panel's 10 pin, right-angle, dual row Communications Header (H1) and individual DB-9 Serial 1 and Serial 2 connectors. On the other hand, the secondary serial port (Serial2) is implemented using hardware pins PA3 (input) and PA4 (output), and is controlled by the associated interrupts IC4/OC5 and OC4, respectively. RS485 is another protocol supported by the primary serial port on the QScreen Controller. RS485 is another protocol supported by the primary serial port on the PDQ Board. Having a second serial port is also handy for system debugging. They translate the bit-by-bit data on the serial cable into bytes of data that can be interpreted by the operating system or by your application program. Single master systems (many other communications schemes are available) offer a straight forward and simple means of avoiding "data collisions" in a typical 2-wire, half-duplex, multi-drop system. To provide a convenient means of attaching two grounds to the serial cable, there are several pins (labeled DGND) on the communications connector that are connected to the controller’s ground plane. Although the RS232 protocol specifies functions for as many as 25 pins, each communications channel requires only three for simple serial interfaces: /TxD1 (transmit data), /RxD1 (receive data), and DGND (digital ground).

Of the processor’s three synchronous SPI (Serial Peripheral Interface) ports, two are available for inter-processor communications on multi-processor systems, and the third is brought out to the Wildcard expansion bus. Yet another is generally any fundamentally ordinary KTY silicon temp word of caution set up after a innovative tv, which are often plainly out of all the actual windows think about box or maybe baked into the devices which needs to be get along the carrying on with environments. Think of RS485 as the younger, faster brother of RS232. Two RS485 transceivers are present on the PDQ Board, one for each channel. Each UART (sometimes referred to as a "USART") controls the serial-to-parallel and parallel-to-serial conversion and performs all of the timing functions necessary for one asynchronous serial communications link. Any number of characters can be sent, and the transmitter will automatically re-trigger with each new character (or in many cases a "bit-oriented" timing scheme is used in conjunction with network biasing for fully automatic operation, including any Baud rate and/or any communications specification, eg. Once a character is sent the hardware reverts back into a receive mode in about 1-2 microseconds (at least with R.E. All of the RS232 signals start with the / (slash, pronounced not) character to indicate that the signals on the serial cable are logically inverted.

There are a variety of ways the MOSI, MISO, SCK and /SS pins on your QScreen Controller can be connected. The SCK pin clocks the serial A/D’s CLK input which causes the A/D’s conversion result to be transferred to the master via the MISO line. The byte-sized messages are transmitted and received via the MOSI (master out/slave in) and MISO (master in/slave out) pins. There are surface-mount resistor pads on the Docking Panel to bring out the RS485 signals to the DB9 Serial 1 Connector. Most computers conform to IBM PC AT-compatible RS232 interfaces which use 9-pin D-Type connectors, consequently the PDQ Board brings out its serial ports to two female 9-pin D-Type connectors on the Docking Panel. These 9-pin standard DB-9 serial connectors are located on the back of the Docking Panel. Receiver Input Resistance (Ohms), (1 Standard Load for RS485) 3k to 7k 4k min. The end resistance must be used only at the ends of the main cable.

The diagram below shows a basic RS485 cable for use with the RJ11 socket on Unitronics PLCs. RS232’s greatest benefit is its universality; most personal computers can use this protocol to send and receive serial data. In a finished instrument, either or both channels can be used to communicate with other serial devices, or with other computers and/or terminals using RS232 or RS485. Two asynchronous communications ports named Serial1 and Serial2 can each be configured for RS232 or RS485 protocols. The PDQ Single Board Computer (SBC) has two asynchronous serial communications ports named Serial1 and Serial2. The Serial 1 and Serial2 ports can be configured for either RS-232 or RS-485 communications at standard baud rates up to 115200 bits per second. The Serial1 and Serial2 ports have identical communications capabilities, although more of the Serial1 signals (both RS232 and RS485) are made available on the Docking Panels headers and connectors. Paperless chart recording is a much more user-friendly solution with an interactive dialogue simplifying both setup and operation procedures.