The Lazy Man's Guide To Rs485 Cable > 자유게시판

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The standard does not discuss cable shielding but makes some recommendations on preferred methods of interconnecting the signal reference common and equipment case grounds. PC environment. 8P8C modular connectors are used in this case. One uses the data lines for 10/100 Ethernet, so that there are still 2 unused pairs in that cable. No termination - If the PDQ Board is not an end device, you should not terminate that cable. A local regulator on each board drops that 9V to 5V, right where it's needed. The local and remote must share a common ground, so all serial cables include at least one ground conductor. Local capacitors on both sides of the regulator are also helpful. Ethernet. I know RJ45-RJ45 cables are often colloquially referred to as Ethernet cables, but that isn't their only use. Although many applications use RS-485 signal levels, the speed, format, and protocol of the data transmission are not specified by RS-485. But there are some limitations to it as it cannot support multiple slaves and multiple masters and the maximum data frame is limited to 9 bits.

The output of that switcher could be anything you want, including multiple outputs at different voltages. SC, G or reference, rs485 cable the common signal reference ground used by the receiver to measure the A and B voltages. This connection may be used to limit the common-mode signal that can be impressed on the receiver inputs. So long as the error between the actual baud rate and that specified is less than 1.5% (or the error between transmitter and receiver is less than 3%) there should be no communication errors. The BAUD routine described at the start of this subsection configures the baud rate of each of the Serial1 and Serial2 channels. Baud to specify the baud rate. RS422 (differential) was designed for greater distances and higher Baud rates than RS232. 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 device that initiates a data transfer is the master, and all other devices on the network are slaves.

In theatre and performance venues, RS-485 networks are used to control lighting and other systems using the DMX512 protocol. 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. Independent channels are established for two-way (full-duplex) communications. The following table summarizes the available serial channels. 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. RS485 is another protocol supported by the primary serial port on the QScreen Controller. There are a variety of ways the MOSI, MISO, SCK and /SS pins on your QScreen Controller can be connected.

If your computer does not have an RS-232 serial port, low cost USB-to-RS-232 serial cables are available; contact Mosaic Industries for details. Grounds between buildings may vary by a small voltage, but with very low impedance and hence the possibility of catastrophic currents - enough to melt signal cables, PCB traces, and transceiver devices. So I would not run low level MCU GPIO level signals over the cable wires. In this case, cable connections must be made to Serial 1 at pins 5 and 6 of the 10-pin Serial Header or pins 7 and 8 on the 24-pin Field Header. Care must be taken when using A/B naming. Care must be taken that an SC connection, especially over long cable runs, does not result in an attempt to connect disparate grounds together - it is wise to add some current limiting to the SC connection. Failure to stay within this range will result in, at best, signal corruption, and, at worst, damage to connected devices. 12 V, i.e. ±7 V on top of the 0-5 V signal range. The two values provide a sufficient margin for a reliable data transmission even under severe signal degradation across the cable and connectors.