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

The pinout of the QScreen’s Serial Header (H5), QScreen’s Field Header (H3), and the Serial Connectors are shown in the following tables. In most cases the times are less than 25 µs which does not pose a problem. In the middle of a character, each interrupt service routine takes about 35 µs. At the start of a transmitted character, the service routine takes about 65 µs. At the end of a received character, the service routine takes about 45 µs. When in use, it is recommended that both ends of the armor layer be grounded and the innermost shielding end is grounded. If the total length of the main cable is less than 50 m termination resistances can be avoided at the ends of the main cable. The main difference between them is in the hardware. These signals may alternatively be redirected to the digital inputs and outputs used by the second serial port if hardware handshaking is required.

Also, several non-serial interrupts can stack up; if they have higher priority than the serial interrupts, they will be serviced before the Serial2 interrupt routine, and again a serial input or output bit may be lost. The QScreen Controller’s kernel software contains a complete set of high level driver routines for the Serial2 port, and these functions are summarized in the Control-C Glossary. The primary and secondary serial communications ports are accessible through the QScreen's 10 pin, dual row Serial Header (H5) which is typically not installed, the 24 pin, dual row Field Header (H3), and through the individual DB-9 Serial 1 and Serial 2 connectors. From the QScreen Controller’s point of view, these three signals (TxD, RxD, what is rs485 cable and ground) are the only connections required to perform serial communications. Product offers a generic serial data/requests filtering feature, which allows you to configure filtering for different visualizers, create filtering schemes and quickly apply them to different visualizer windows.Additionally, you may change the appearance of visual elements for monitored packets in the data visualizers including MODBUS View, Request View (Serial, Bridge), Data View, PPP View.

Because all of the serial I/O routines on the QScreen Controller are revectorable, it is very easy to change the serial port in use without modifying any high level code. If you do this now, remember to move the QScreen Controller’s serial connector back to Serial Port 1, and to change the terminal’s baud rate back to 19200 baud using the "Comm" item under the terminal’s "Settings" menu. Using the primary serial port is easy. Data translation between different machines can be performed with ease, and applications that communicate via the primary serial port can be debugged using the secondary channel. Because the software UART is interrupt based, competing interrupts that prevent timely servicing of the Serial2 interrupts can cause communications errors on the secondary serial channel. Most newer consumer electronics comes with an USB, Firewire or other high-speed communication port, however a lot of industrial and commercial equipment, both old and new, is made only with a RS485 or RS422 serial communications port. This is where the RS485 1-to-4 Splitter/Hub comes in!

The default serial routines used by the onboard kernel assume that full duplex communications are available, so you cannot use the RS485 protocol to program the controller. If an interrupt service routine takes longer than 200 µs, then an entire serial bit will be missed, causing a communications error. Any of these conditions may generate an interrupt if the SPIE (SPI interrupt enable) bit in the SPCR control register is set. In this case, cable connections may be made to Serial 1 on either the 10-pin Serial Communications Header or the Serial 1 Connector. These detailed signal descriptions and cable diagrams are presented to provide complete information for those who have special communications requirements and for those who wish to make their own application-specific communications cables. Based on information from the Wikipedia page you posted, it looks like there are a limited number of communication standards transmitted over 485, with one being pointed out as the most frequently used.