8N2

8N2 is a shorthand notation used in asynchronous serial communication to describe a specific frame format: eight data bits, no parity, and two stop bits. The "N" stands for no parity, while the numbers indicate the data and stop bit configuration. In practice, a serial character with 8N2 is typically transmitted as a start bit, eight data bits, no parity bit, and two stop bits, making the full frame longer than more common configurations.

In the context of UART-based communication, the stop bits signal the end of a character and provide a recovery interval for receivers. Having two stop bits increases the time between characters, which can improve reliability on noisy lines or with longer cable lengths, but it reduces the effective data throughput compared with configurations that use only one stop bit.

Usage and prevalence vary. 8N2 is found on some legacy equipment, older industrial instruments, and certain microcontroller or embedded-system setups. It is less common in modern general-purpose interfaces, where 8N1 (eight data bits, no parity, one stop bit) is typically preferred for higher throughput and broad compatibility. Some devices and software stacks may not support 8N2, or may require explicit configuration to enable two stop bits.

Interoperability considerations include ensuring both ends of a link agree on the framing parameters. Mismatched settings can produce framing errors and garbled data. In systems that do support it, 8N2 is one option among several asynchronous serial formats, alongside 8N1, 7E1, and others.

See also: asynchronous serial communication, RS-232, UART, 8N1, parity, stop bits.