![]() The master is in charge of designating which receiver is on at any one time. To avoid contention on the RS485 bus, the application software must assure that only one transmitter is enabled at a time. No parity means that there is no parity bit.Ī break sequence forces the serial output to a logic low (space) at the UART.īoth the local and remote UARTs must be configured for the same communications parameters.īecause a single pair of conductors is used for both transmission and reception, RS485 is useful for multi-drop applications in which a master communicates with multiple slave serial devices, or nodes. High (mark) parity means that the parity bit is always logic 1 at the UART, and low (space) parity means that the parity bit is always logic 0 at the UART. Even parity means that the bits sum to an even number, and odd parity means that the bits sum to an odd number. Parity options include even, odd, high, low, or no parity. One to two logic-high stop bits mark the end of a character. An optional parity bit can be specified to enable error detection by the UART. A logic-low start bit marks the start of a character, followed by 5 to 8 data bits per character. The serial output at the UART idles at the logic high (mark) level. At the UART, a logic high (5 volts) is called a mark, and a logic low (0 volts) is called a space. Serial data is shifted out least-significant-bit first. ![]()
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