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

Thus, as a rough approximation, operating at 4800 baud full duplex requires about 40 to 50% of the 6811's CPU time (that is, an average of approximately 40 to 50 µs service time every 100 µs). Working modes: asynchronous; point-to-point or point-to-multipoint; 2-line half duplex and 4-line full duplex. Simply using the provided USB converter cable is not working for me right now with the Pi. I am working on a project that involves a Solar Charge Controller. In this example, the QScreen Controller selects the serial A/D by outputting a LOW signal on /SS. So I would not run low level MCU GPIO level signals over the cable wires. The transmit and receive data signals carry the messages being communicated between the PDQ Board and the PC or terminal. RS485 is another protocol supported by the primary serial port on the PDQ Board. The PDQ Board's two serial ports support limited use of generating a parity bit. The RS232 protocol specifies the use of two separate grounds, a signal ground and a protective (or "chassis") ground. Two asynchronous communications ports named Serial1 and Serial2 can each be configured for RS232 or RS485 protocols.

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 default baud rate for both Serial1 and Serial2 is 115200 baud after a factory cleanup. Port to modem communications usually use 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200 baud. I would highly discourage the use of extra signal pins in the connectors for "cable connected" checking that do not meet the same specs as the RS485 signalling signals. SC, G or reference, the common signal reference ground used by the receiver to measure the A and B voltages. The output of that switcher could be anything you want, including multiple outputs at different voltages. A break sequence forces the serial output to a logic low (space) at the UART. InitRS485() configures Port D to ensure that bit 5 is an output. A PoE device needs to accept both variations in either polarity (4 possibilities) to be fully standards-compliant, in addition to the signalling that a standards-compliant source requires to enable the power on that port. To make sure that your USB to RS-485 cable & the device RS-485 port are working, have you tried using them with a Windows PC and the manufacturer's s/w?

The device ships with an Ethernet RS-485 communication interface as well as a RS-485 to USB cable, which is said to be able to communicate with a PC using proprietary Windows based software (and driver, I think). The mention of "Ethernet RS-485 communication interface" confused me. RS-485 signals are used in a wide range of computer and automation systems. So take advantage of that and let your systems MCUs implement heart beat handshaking directly though the RS485 communications layer using appropriately designed small packets. There is a huge benefit of the RS-485 electrical layer protocol that allows for long distance communications in the presence of multiple volts of common mode voltage differences between the two ends. A simple network of a PLC, VFD, and an HMI allows remote control of motors in an industrial setting. 4V out as the regulator saturates), and the extra 2V above that allows for some noise-induced "wiggle". Local capacitors on both sides of the regulator are also helpful. A local regulator on each board drops that 9V to 5V, right where it's needed. They take over at high frequencies while the regulator is really meant for DC and "DC-like" low-frequencies. Control and monitoring systems: A single pair of rs485 signal cable can connect up to 32 devices, with a signal transmission distance of up to 1200m. Therefore, using rs485 cables is an ideal choice for industrial control and monitoring systems, especially those with large-scale and high dispersion.

This configuration works for many SPI devices, including the optional battery-backed real-time clock. If the /SS pin of the master is an input and if a low input level is detected, the processor sets the MODF bit in the SPI status register a "mode fault" condition. The BufferToSPI() function implements fast data transfer from a specified buffer in the controller’s memory to an SPI device. It is supported by virtually all personal computers, and is the default protocol for both of the QScreen Controller’s serial ports. Serial 2 is implemented by a software UART in the controller’s QED-Forth Kernel that uses two of the processor’s PortA I/O pins to generate a serial communications channel. I recently bought some RS485 cable, it had two pairs, both had stripes. Therefore for RS485 communications no crossover cable is used. It is NOT necessary to introduce long delays in a network to avoid "data collisions." Because delays are NOT required, networks can be constructed, that will utilize the data communications bandwidth with up to 100% through put.