2) why should it be Grounded? > 자유게시판

So I would not run low level MCU GPIO level signals over the cable wires. • Low USB bandwidth consumption. This consumes bandwidth and network time in applications where bandwidth may be expensive, such as over a low-bit-rate radio link. 2. It is not allowed to use a network cable with a wire diameter that is too thin, which will reduce the transmission distance and reduce the equipment that can be connected. Different topology designs suit different network needs and applications, affecting performance, reliability, and scalability. 7) Under what circumstances should a terminal resistance be added to the 485 bus? ● Use scientific and reserved solutions for 485 bus projects with long lines and heavy loads. In short, RS485 is a standard defining the electrical characteristics of serial lines for use in serial communications systems. 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. 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). It works on half-duplex communication to implement the function of converting the TTL level into RS-485 level which means it can either transmit or receive at any time, not both, it can achieve a maximum transmission rate of 2.5Mbps. MAX485 transceiver draws a supply current of between 120μA and 500μA under the unloaded or fully loaded conditions when the driver is disabled. But I notice that he describes using a (different) RS-485 to USB converter and splicing from the Ethernet cable to the converter, rather than using the converter cable that ships with the charge controller. Note that this Hackster project does something similar with splicing an ethernet cable to a UART breakout module. Is it necessary to do the ethernet cable splicing as indicated in the above link, or should I simply be able to use the provided USB cable? Modbus is restricted to addressing 247 devices on one data link, which limits the number of field devices that may be connected to a parent station (again, Ethernet TCP/IP is an exception).

Access control systems: Rs485 cables are mainly used to connect and transmit data between access control devices such as security gates, RFID cards, or time attendance machines and the control center. Modbus protocol itself provides no security against unauthorized commands or interception of data. It provides a convenient means of connecting the QVGA 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 RS232 protocol provides for four handshaking signals called ready to send (RTS), clear to send (CTS), data set ready (DSR), and data terminal ready (DTR) to coordinate the transfer of information. The WCOL flag is set when a write collision occurs. The QED-Forth kernel includes pre-coded drivers that configure and control the SPI for maximum speed data transfers. The QED-Forth kernel includes pre-coded drivers that configure the SPI for maximum speed data transfer using a format that is compatible with the on-board D/A and 12 bit A/D. Simply using the provided USB converter cable is not working for me right now with the Pi. 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.

For these secondary devices you have to implement your periodic heart beat check in some device specific way. For devices where you have to consider the devices at the far end of your cables to be unable to be modified, either hardware or software wise, what is rs485 cable you have to get clever regarding how you determine if the device is connected. If one or the other end fail to see the heartbeat packets come or get acknowledgement of them then know that your cable is either disconnected or has broken wires. The only way this would not work is if the secondary device only takes "write only to device" transmissions with no possibility of any acknowledgement or return result. This can vary greatly depending upon the device. In the transmission process, the method of adding relays can be used to amplify the signal. The connection method of the 120Ω matching resistance of the dome terminal is as follows: The 120Ω matching resistance of the dome terminal can be connected by the dial switch on the chassis of the dome. A simple method is often a status check. Now in the loop, we check if there is anything available on the serial port and then read the data and since the incoming data is an integer, we parse it and display on the connected LCD.